Fix SHOW_COMMON_EXTENSIONS docs typos (#162)

Fix copy-paste errors.

docs/settings.rst

@@ -263,10 +263,10 @@ Controls how many levels are expaned by default when showing nested models.
 **Default**: :python:`3` |br|
 *Maps to parameter*: ``defaultModelExpandDepth``
 
-DEFAULT_MODEL_DEPTH
--------------------
+SHOW_COMMON_EXTENSIONS
+----------------------
 
-Controls the display of extensions (``pattern``, ``maxLength``, ``minLength``, ``maximum``, ```minimum``) fields and
+Controls the display of extensions (``pattern``, ``maxLength``, ``minLength``, ``maximum``, ``minimum``) fields and
 values for Parameters.
 
 **Default**: :python:`True` |br|