finatra: Document route/query/form parameters are case sensitive
finatra: Document route/query/form parameters are case sensitive

Problem
Route/query/form parameters match has been case sensitive in Finatra but our doc
doesn't reflect that

Solution
Add clarification for that in finatra user doc

JIRA Issues: CSL-8739

Differential Revision: https://phabricator.twitter.biz/D367515

twitter/finatra,twitter/finatra,twitter/finatra