Automatically show 'last update' date

[eldonquijote]

Purpose / why

Automatically show date of last updates on each documentation page. Proof of concept for using Materials theme feature based on plugin.

What changes were made?

Included and activated git-revision-date-localized (https://github.com/timvink/mkdocs-git-revision-date-localized-plugin) plugin for MkDocs. With the plugin active, each documentation page will show a 'last updated' date at the bottom, based on the page's Git revision history.

Important: If you want to test this locally, you must first install the plugin with pip install mkdocs-git-revision-date-localized-plugin, otherwise the build will fail.

Placing the date at the top of the page might involve modifying the Materials theme. It's possible to manually add a variable command showing the date at any location on the page.

Verification

• Build and test locally
• Verify/test integration with Travis for automated builds on Github

Interested Parties

@dannylamb @manez @highermath

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Checklist

Pull-request reviewer should ensure the following

• Does this PR link to related issues?
• Does the proposed documentation align with the Islandora Documentation Style Guide?
• Are the changes accurate, useful, free of typos, etc?
• Does this PR update the last updated on date on the documentation page?

Person merging should ensure the following

• Does mkdocs still build successfully? (This is indicated by TravisCI passing. To test locally, and see warnings, see How To Build Documentation.)
• If pages are renamed or removed, have all internal links to those pages been fixed?
• If pages are added, have they been linked to or placed in the menu?
• Did the PR receive at least one approval from a committer, and all issues raised have been addressed?

[manez]

This looks like a great addition, but I'm not 100% sure I know how to test it. Maybe this is under @highermath 's purview as our designated "Material Theme Expert? 😄

[eldonquijote]

Thanks for taking a look! This might warrant more discussion in the DIG. In order to have this feature working for all contributors/testers, everyone who wants to run mkdocs locally to test/work on I8 documentation would need to install an additional Python plugin.

[dannylamb]

@eldonquijote Can we add pip install mkdocs-git-revision-date-localized-plugin to the install instructions here: https://github.com/Islandora/documentation/blob/main/docs/technical-documentation/docs-build.md ?

Other than that, I've tested it and it works great. The date automatically shows up at the bottom of the page.

[manez]

Once this is merged, we'll need a to-do to go clean up the manually added "last updated" lines where we have them. This is a much more elegant solution 👍

[eldonquijote]

@dannylamb I've updated the instructions.

@manez I found 10 instances of _last updated .* in the docs folder, should I just go ahead and remove them for this branch?

[dannylamb]

If you're up for it, by all means go ahead and pull them out now.