Updates documentation to account for the renamed ENABLE_SWAGGER_ENDPOINT from #3572 (commit a74426d631e3311cc3c460ae9917f76f0221f4de)
Signed-off-by: Peter Colberg <peter@colberg.org>
* add api user guides in doc
* update user-guides api page
* fix typo: user guides -> user guide
* move api-usage page under advanced category
* flesh out API usage docs
* Build on work by @tungsheng
* Address issues raised in #4037, #3673, and #4243
* Close#4247
Signed-off-by: Steve Traugott <stevegt@t7a.org>