Incorrect build documentation due to identical file names of examples

[yvonnefroehlich]

It seems like it is not allowed by Sphinx-Gallery that two examples have identical filenames, even when they are saved in different folders. Currently, this is the case for:

• Intro to PyGMT - Create a contour map: https://www.pygmt.org/dev/get_started/contour_map.html
• Tutorials - Creating a map with contour lines: https://www.pygmt.org/dev/tutorials/advanced/contour_map.html

When running make html to build the documentation locally, the following warning occurs:

WARNING: Duplicate example file name(s) found. Having duplicate file names will break some links.
List of files: ['../examples/get_started/contour_map.py']

According to this the documentation for the tutorial is wrongly build:

• correct - v0.7.0: https://www.pygmt.org/latest/tutorials/advanced/contour_map.html
• wrong - dev after adding "Create a contour map": https://www.pygmt.org/dev/tutorials/advanced/contour_map.html

Thus, we have to rename one of these two example files.

[seisman]

Ping @willschlitzer, author of the two examples .