docs: minor updates to xor (VirusTotal#2098)

docs/writingrules.rst

@@ -425,7 +425,7 @@ The above rule is logically equivalent to:
             any of them
     }
 
-You can also combine the ``xor`` modifier with ``wide`` and ``ascii``
+You can also combine the ``xor`` modifier with ``fullword``, ``wide``, and ``ascii``
 modifiers. For example, to search for the ``wide`` and ``ascii`` versions of a
 string after every single byte XOR has been applied you would use:
 
@@ -465,7 +465,7 @@ equivalent:
             any of them
     }
 
-Since YARA 3.11, if you want more control over the range of bytes used with the ``xor`` modifier use:
+Since YARA 3.11, if you want more control over the range of bytes used with the ``xor`` modifier, use:
 
 .. code-block:: yara