Editing sponsors and credits pages of documentation

[isaacgsmith]

Description

• Adds descriptions of what each sponsor does for us into the sponsors page
• Acknowledges GitHub and NUMFocus on the credits page

How has this been tested?

• Testing pipeline.
• Other.
  Documentation built locally.

Examples

Here are the two relevant pages:
https://smithis7.github.io/tardis/branch/sponsor_description_doc/sponsors.html
https://smithis7.github.io/tardis/branch/sponsor_description_doc/credits.html

Type of change

• Bug fix.
• New feature.
• Breaking change.
• None of the above.

Checklist

• My change requires a change to the documentation.
  • I have updated the documentation accordingly.
  • (optional) I have built the documentation on my fork following the instructions.
• I have assigned and requested two reviewers for this pull request.

[codecov]

Codecov Report

Merging #1656 (05088f6) into master (b69b093) will not change coverage.
The diff coverage is n/a.

❗ Current head 05088f6 differs from pull request most recent head fe7bf86. Consider uploading reports for the commit fe7bf86 to get more accurate results

@@           Coverage Diff           @@
##           master    #1656   +/-   ##
=======================================
  Coverage   61.93%   61.93%           
=======================================
  Files          62       62           
  Lines        5729     5729           
=======================================
  Hits         3548     3548           
  Misses       2181     2181           

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[tardis-bot]

Before a pull request is accepted, it must meet the following criteria:

• Is the necessary information provided?
• Is this a duplicate PR?
  • If a new PR is clearly a duplicate, ask how this PR is different from the original PR?
  • If this PR is about to be merged, close the original PR with a link to this new PR that solved the issue.
• Does it pass existing tests and are new tests provided if required?
  • The test coverage should not decrease, and for new features should be close to 100%.
• Is the code tidy?
  • No unnecessary print lines or code comments.

[Rodot-]

NumFOCUS should be written as NumFOCUS and it should reference the small development grant. What did GitHub do for us again? Could you add that in?