Rename tutorials using underscores

[maxrjones]

Description of proposed changes

This PR renames tutorials with underscores, rather than dashes.

Fixes #1039

Reminders

• Run make format and make check to make sure the code follows the style guide.
• Add tests for new features or tests that would have caught the bug that you're fixing.
• Add new public functions/methods/classes to doc/api/index.rst.
• Write detailed docstrings for all functions/methods.
• If adding new functionality, add an example to docstrings or tutorials.

Slash Commands

You can write slash commands (/command) in the first line of a comment to perform
specific operations. Supported slash commands are:

• /format: automatically format and lint the code
• /test-gmt-dev: run full tests on the latest GMT development version

[seisman]

/home/runner/work/pygmt/pygmt/doc/index.rst:16: WARNING: toctree contains reference to nonexisting document 'tutorials/first-figure'
looking for now-outdated files... none found
/home/runner/work/pygmt/pygmt/doc/index.rst:26: WARNING: toctree contains reference to nonexisting document 'tutorials/contour-map'
/home/runner/work/pygmt/pygmt/doc/index.rst:26: WARNING: toctree contains reference to nonexisting document 'tutorials/earth-relief'
/home/runner/work/pygmt/pygmt/doc/index.rst:26: WARNING: toctree contains reference to nonexisting document 'tutorials/3d-perspective-image'

Need to update the file doc/index.rst.

[maxrjones]

/home/runner/work/pygmt/pygmt/doc/index.rst:16: WARNING: toctree contains reference to nonexisting document 'tutorials/first-figure'
looking for now-outdated files... none found
/home/runner/work/pygmt/pygmt/doc/index.rst:26: WARNING: toctree contains reference to nonexisting document 'tutorials/contour-map'
/home/runner/work/pygmt/pygmt/doc/index.rst:26: WARNING: toctree contains reference to nonexisting document 'tutorials/earth-relief'
/home/runner/work/pygmt/pygmt/doc/index.rst:26: WARNING: toctree contains reference to nonexisting document 'tutorials/3d-perspective-image'

Need to update the file doc/index.rst.

Thanks, fixed in ef0d43e

[seisman]

There may be something wrong with GitHub.

I clicked the "Squash and merge" button a few minutes ago and it froze.

Now it seems the changes in this PR are already in the master branch, but this PR is still unmerged. Is this what you're seeing?

[maxrjones]

There may be something wrong with GitHub.

I clicked the "Squash and merge" button a few minutes ago and it froze.

Now it seems the changes in this PR are already in the master branch, but this PR is still unmerged. Is this what you're seeing?

Yes, I see the same thing. The commit log shows this as merged, but the PR does not reflect that.

[michaelgrund]

There may be something wrong with GitHub.
I clicked the "Squash and merge" button a few minutes ago and it froze.
Now it seems the changes in this PR are already in the master branch, but this PR is still unmerged. Is this what you're seeing?

Yes, I see the same thing. The commit log shows this as merged, but the PR does not reflect that.

I see the same.

[seisman]

Maybe GitHub did the "git merge" command, froze and then forgot to close the PR.

Let's keep this PR open for a while and see if anything changes.

[weiji14]

https://www.githubstatus.com/. Parts of GitHub are currently down. Need to wait it out and be careful for a while.

[seisman]

GitHub is up now. Nothing changes. I'll close the PR.