Add "Edit this page" links to workflow documentation site (meta issue)

[eecavanna]

This may involve coordinating with the maintainers of the upstream workflow repositories.

• Define github_url in index.rst (local) #92
• Define github_url in overview.rst (local) #93
• Define github_url in 1_Metagenome_Workflow_Overview (local) #91
• Enable "Edit on GitHub" link by defining :github_url: in index.rst ReadbasedAnalysis#29
• Enable "Edit on GitHub" link by defining :github_url: in index.rst ReadsQC#42
• Enable "Edit on GitHub" link by defining :github_url: in index.rst metaAssembly#30
• Enable "Edit on GitHub" link by defining :github_url: in index.rst mg_annotation#41
• Enable "Edit on GitHub" link by defining :github_url: in index.rst metaMAGs#64
• Enable "Edit on GitHub" link by defining :github_url: in index.rst metaT#40
• Enable "Edit on GitHub" link by defining :github_url: in index.rst metaT_ReadsQC#10
• Enable "Edit on GitHub" link by defining :github_url: in index.rst metaT_Assembly#9
• Enable "Edit on GitHub" link by defining :github_url: in index.rst metaT_ReadCounts#3
• Enable "Edit on GitHub" link by defining :github_url: in index.rst metaPro#78
• Enable "Edit on GitHub" link by defining :github_url: in index.rst metaMS#63
• Enable "Edit on GitHub" link by defining :github_url: in index.rst enviroMS#12

[eecavanna]

I identified a solution. I implemented it for one workflow here: https://github.com/microbiomedata/metaMAGs/pull/65/files. I want to make analogous changes to the other upstream workflow repos.

[eecavanna]

At this point, I've implemented the solution on the three relevant files in this docs repo and in 5 remote repos. There are still 7 remote repos left to implement it in. Note that the branch name is main in 3 of them and master in the other 4.

[eecavanna]

Done via 13+ PRs (see issue description for a link to each one).