Fixing typo in documentation

Just a small usage error. :)

docs/models.rst

@@ -5,7 +5,7 @@ Flask-Security assumes you'll be using libraries such as SQLAlchemy,
 MongoEngine or Peewee to define a data model that includes a `User` and
 `Role` model. The fields on your models must follow a particular convention
 depending on the functionality your app requires. Aside from this, you're
-free to add any additional fields to your model(s) if you want. At the bear
+free to add any additional fields to your model(s) if you want. At the bare
 minimum your `User` and `Role` model should include the following fields:
 
 **User**