docs: fix Docker 1C2D example path and pgxc configuration filename

[Lycorius03]

Related to OpenTenBase/OpenTenBase#203

Problem

Issue OpenTenBase/OpenTenBase#203 reports two defects on the published Docker 1C2D guide page
https://docs.opentenbase.org/guide/15-docker-deploy, and two independent readers confirmed
the second one. Both defects live in the source of that page, i.e. in this repository:

1. Step 2 tells the reader to run cd ${SOURCECODE_PATH}/example/1c_2d_cluster. That directory
   does not exist on OpenTenBase/OpenTenBase@master: the whole example/ tree was deleted by
   commit aca7e2c
   ("Update basecode version from 2.6.0 to 5.0.0"). Steps 2 to 4 therefore cannot be run as
   written — only the image build used by step 1 (docker/buildImage.sh) still exists.

2. Step 4 says deploy all uses /home/$USER/pgxc_ctl/pgxc.conf. That file name is wrong:
   pgxc_ctl reads pgxc_ctl.conf, and there is no rename step anywhere in the tool.

The source repository was corrected in OpenTenBase/OpenTenBase#312 (docker/README.md). This
PR applies the same findings to the page users actually read.

Changes

Two files, both locales, nothing else:

File	Change
docs/guide/15-docker-deploy.md	step 1: note that SOURCECODE_PATH must be replaced with your own clone path. step 2: add a note that example/1c_2d_cluster no longer exists on master, name the commit that removed it, point to the configuration template that is still published, and give the revision from which the removed Compose file can still be retrieved. step 4: correct pgxc.conf → pgxc_ctl.conf and add the source-level reason.
docs/guide/15-docker-deploy.en.md	same changes, English.

The step 2 and step 4 shell code blocks are otherwise byte-identical: no command is added,
removed or reordered, and no new deployment procedure is introduced. mkdocs.yml is untouched
(no page is renamed, so the nav is unaffected).

Evidence

Claim	Evidence
example/1c_2d_cluster is not on master	git ls-tree -r --name-only HEAD in OpenTenBase/OpenTenBase (8419 paths) → 0 matches for 1c_2d; git rev-list --all --objects → 0 matches, so it was deleted rather than moved
It was deleted by aca7e2c	git log --diff-filter=AD -- 'example/*' → aca7e2c lists D for example/1c_2d_cluster/README, docker-compose.yaml, pgxc_conf/cn/pgxc_ctl.conf
Only the image build survives in the source repo	docker/buildImage.sh, docker/base/Dockerfile, docker/host/Dockerfile are still on master
${SOURCECODE_PATH} is the user's clone path	OpenTenBase/OpenTenBase README.md line 78 and docker/host/Dockerfile line 29 both set it to /data/opentenbase/OpenTenBase
pgxc_ctl reads pgxc_ctl.conf	contrib/pgxc_ctl/pgxc_ctl.h #define DEFAULT_CONF_FILE_NAME "pgxc_ctl.conf"; contrib/pgxc_ctl/pgxc_ctl.c setDefaultIfNeeded(VAR_configFile, "pgxc_ctl.conf") and build_configuration_path() resolving <pgxc_ctl_home>/<configFile>, with pgxc_ctl_home defaulting to $HOME/pgxc_ctl
pgxc.conf belongs to another tool	repository-wide search for pgxc.conf in OpenTenBase/OpenTenBase returns only contrib/pgxc_ddl/* and doc/src/sgml/pgxcddl.sgml; contrib/pgxc_ddl/pgxc_ddl sets PGXC_CONF=$DATA_FOLDER/pgxc.conf
The 1C2D configuration template is in this repository	docs/guide/pgxc_ctl_double.conf and docs/guide/pgxc_ctl_single.conf

Validation

Documentation only, and this repository's CI does not run on pull requests
(.github/workflows/ci.yml is on: push to main/master only). So the deploy pipeline was
reproduced locally with the same two packages it installs — mkdocs-material (9.7.7) and
mkdocs-static-i18n (1.3.1) under mkdocs 1.6.1 — and mkdocs build was run twice:

• on the pristine tree (git checkout -- both files), and
• on the changed tree.

Results:

• Both builds exited 0.
• The two build logs are identical after normalising the output directory and the reported
  duration. That includes the only two messages emitted, which are pre-existing anchor warnings
  in an unrelated file (contribution/docs-format-guide.md, links #中文文案排版指北 and
  #工具). No new warning or error is introduced.
• The generated HTML was then inspected in both locales: the baseline contains the wrong
  pgxc_ctl/pgxc.conf reference, the changed build no longer does, and the changed build
  contains the removal commit, the historical revision link and pgxc_ctl_double.conf. The
  added note renders as a <blockquote>, with no literal !!! and no unrendered **Note**.
• Every URL added was fetched and returns HTTP 200, including the historical revision link.
• Encoding: both files remain valid UTF-8 with no BOM (matching the originals), no replacement
  characters, and balanced code fences. git diff --check is clean and
  git ls-files --others --exclude-standard is empty.

Not validated: no Docker image was built and no 1C2D cluster was deployed, so this PR does not
assert that the removed example can be reconstructed into a working deployment.

Note on style choices

Two deliberate departures from the obvious approach, both driven by measurement:

• Plain blockquotes rather than !!! note. mkdocs.yml nests markdown_extensions inside
  the theme: block, so the admonition, tables and attr_list extensions are not actually
  enabled. Confirmed against the live site: fetching
  https://docs.opentenbase.org/contribution/docs-format-guide/ returns HTML containing a
  literal !!! and no class="admonition", i.e. the existing admonition blocks render as plain
  text. Note that fixing that nesting is a separate issue and is deliberately left alone here.
• Absolute GitHub URLs rather than relative paths. docs/contribution/docs-format-guide.md
  asks for relative paths for in-site links, but pgxc_ctl_double.conf is published only for
  the Chinese locale — https://docs.opentenbase.org/guide/pgxc_ctl_double.conf returns 200
  while https://docs.opentenbase.org/en/guide/pgxc_ctl_double.conf returns 404 — so a
  relative link would be broken on the English page. Happy to switch the Chinese file to a
  relative path if you prefer.

Follow-up, not changed here

• The guide's final psql -h 172.16.200.10 -p 30004 targeted opentenbaseDN1, not the CN
  (172.16.200.5) in the removed Compose file. Left alone: without the Compose file this cannot
  be confirmed against a running cluster.
• Whether example/1c_2d_cluster should be restored, or this guide retired in favour of the
  KubeBlocks path, is a maintainer decision. This PR documents the current state and does not
  assume an answer.

AI Usage

Produced by an AI agent (WorkBuddy). Every statement added is traceable to a file/line, a
commit, or a live HTTP check; no parameter meaning was inferred from general knowledge.

[Lycorius03]

说的都队