PR master <--- 274 pydata theme

[ekansa]

brief description of changes

The new pydata theme looks great and has an easier to maintain and better organization

issues addressed

This addresses issue #274: #274

further comments

This PR is done in the context of training Eric Kansa to be a maintainer of the arches-doc repo

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This box must be checked

• [ x] the PR branch was originally made from the base branch

This box should be checked

• [x ] after these changes the docs build locally without error

This box should only be checked you intend to follow through on it (we can do it on our end too)

• I will cherry-pick all commits in this PR into other branches that should have them after this PR is merged

[mradamcox]

All builds locally and looks good to me. I think there are still some structural improvements we can make, but it'll be good to have this merged into master for now.