BTREE indexes to be case sensitive and GIN are case insensitive

By their nature, BTREE indexes are case sensitive and that should be included in our documentation. Removing the case sensitivity on BTREEs removes the performance gains they were used in the first place. Users need made be aware of this

No documentation file is named. Start by locating the documentation that describes BTREE and GIN indexes, then verify the existing statements about case sensitivity and index performance. Done means the relevant documentation clearly warns users about BTREE case sensitivity and explains the stated GIN behavior.

Written by the indexing model from the issue text.