Update README and CHANGELOG

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 * Add `--exclude-migration-tests` option to ignore backward incompatible migration tests.
 * Do not falsely detect dropping `NOT NULL`  constraint.
+* Detect `DROP TABLE` backward incompatible migration.
 
 Internal change:
 

README.rst

@@ -77,6 +77,7 @@ The linter analyses your migrations and checks the SQL for:
 
 - Added ``NOT NULL`` columns, which don't have a DEFAULT value
 - Dropping columns
+- Dropping tables
 - Renaming columns
 - Renaming tables
 - Altering columns (which can be backward compatible and potentially ignored)