There are two things that needed some change:
1) default value: it's 10 secs rather than 5
2) this env var applies to both app db and external db's

* update section name to match sidebar

* fix link

* add instructions to convert key to der

* omit paragraph re: sslmode

* Tag tests that rely on Webmail SMTP server

* Tag tests that rely on external QA databases

* Tag tests that rely on docker LDAP server

* Update the dev documentation

* Fix typo

* allow disabling custom geojson via env var

* add env var to docs and tweak setting description

* remove toc generation from api docs

* update api docs

* update test