move "If you're coming from MetaSearch" section to bottom of readme
move "If you're coming from MetaSearch" section to bottom of readme

It's been eight years since Ransack succeeded MetaSearch. As most
developers have likely migrated from MetaSearch to Ransack by now,
anyone reading the readme is likely starting fresh with Ransack - so
it's perhaps less useful to highlight differences from MetaSearch in
the readme's introduction.

Move the "Updating From MetaSearch" section to the bottom of the readme,
and make sure any important details (like setting the default search
param) are covered appropriately within the readme.

activerecord-hackery/ransack