workarounds docs: add manual section

doc/modules.rst

@@ -23,3 +23,4 @@ Knot DNS Resolver modules
 .. include:: ../modules/renumber/README.rst
 .. include:: ../modules/cookies/README.rst
 .. include:: ../modules/version/README.rst
+.. include:: ../modules/workarounds/README.rst

modules/workarounds/README.rst

 .. _mod-workarounds:
 
-FIXME
+Workarounds
+-----------
+
+A simple module that alters resolver behavior on specific broken sub-domains.
+Currently it mainly disables case randomization on them.
+
+Running
+^^^^^^^
+.. code-block:: lua
+
+    modules = { 'workarounds < iterate' }