Clean up unused image files (#472)

* integrate custom docs with new UI

* more edits

* use website wording for intro

* fix numbering in table

* rename and some edits

* rename manage_repo file, per Bo

* Merge.

* formatting edits

* updates per Keyur's feedback

* Fix typos

* fix nav order

* fix link to API key request form

* update form link

* update key request form and output dir env var

* Revert to gerund

Though the style guide says to just use imperatives, "get started" just sounds weird. Also this is more consistent with "troubleshooting"

* new troubleshooting entry

* fix typo

* new data container procedures

* more work

* more work

* complete data draft

* more changes

* more changes

* more revisions

* update troubleshooting doc etc.

* new version of diagrams

* remove data loading problems troubleshooting entry; can't reproduce

* revert title change

* add example for not mixing entity types

* changes from Keyur

* add screenshots for GCP, and related changes

* fixed one image

* added screenshots for Cloud Run service

* resize images

* more changes from Keyur

* fix a tiny error

* delete unused images