Add a note about casting boolean columns (#770)
Add a note about casting boolean columns (#770)

Explains why "SELECT true" doesn't get converted to a boolean with cast_booleans: true.
bigcartel/mysql2,brianmario/mysql2,tamird/mysql2,kamipo/mysql2,bigcartel/mysql2,tamird/mysql2,jconroy77/mysql2,kamipo/mysql2,tamird/mysql2,sodabrew/mysql2,sodabrew/mysql2,tamird/mysql2,sodabrew/mysql2,jeremy/mysql2,bigcartel/mysql2,jconroy77/mysql2,jconroy77/mysql2,yui-knk/mysql2,brianmario/mysql2,yui-knk/mysql2,jconroy77/mysql2,kamipo/mysql2,yui-knk/mysql2,kamipo/mysql2,yui-knk/mysql2,jeremy/mysql2,jeremy/mysql2,brianmario/mysql2,bigcartel/mysql2