Add help docs to Add Evidence and other forms (detailed)

[kkrysiak]

Related to: https://github.com/griffithlab/civic-client/issues/1592

Once docs have been updated we should add help doc links to each line of Evidence and Assertion Add pages to point to specific sections of the help docs.

Dependent on: https://github.com/griffithlab/civic-docs/issues/80 https://github.com/griffithlab/civic-docs/issues/46 ...probably others.