We need help text for everything

Here’s a list of places in the UI missing help text:

+ Strict content type validation (repository config)
+ Name (repository config, make it clear that we expect an ID, not a human-readable string.)
+ Raw repository (repository config/browse, need a better name and/or description) Removed based on discussion on https://groups.google.com/a/sonatype.com/forum/?hl=en#!topic/sonatype-nexus-dev-group/2_GR2cC6jP0
+ Query cache size/Nexus trust store (repository config, need better descriptions)
+ Not Found Cache enabled (repository config, the intent is clear but not what this does)

(add here!)