fp docs - Remove notes about mutation in description.

lib/doc/apply-fp-mapping/index.js

@@ -1,4 +1,5 @@
 var Entry = require('docdown/lib/entry'),
+    getUpdatedDesc = require('./description'),
     getReorderedParams = require('./parameters'),
     getReorderedExample = require('./example');
 
@@ -6,6 +7,7 @@ var Entry = require('docdown/lib/entry'),
  * Updates `docdown` `Entry`'s prototype so that parameters/arguments are reordered according to `mapping`.
  */
 module.exports = function applyFPMapping(mapping) {
+  Entry.prototype.getDesc = getUpdatedDesc;
   Entry.prototype.getParams = getReorderedParams(mapping);
   Entry.prototype.getExample = getReorderedExample(mapping);
 };