Documentation: fix a typo and formatting

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177722 91177308-0d34-0410-b5e6-96231b3b80d8

docs/Modules.rst

@@ -239,7 +239,7 @@ Within a module map file, modules are referred to by a *module-id*, which uses p
 .. parsed-literal::
 
   *module-id*:
-    *identifier* (',' *identifier*)*
+    *identifier* ('.' *identifier*)*
 
 Module declaration
 ------------------
@@ -269,7 +269,7 @@ The ``system`` attribute specifies that the module is a system module. When a sy
 
 Modules can have a number of different kinds of members, each of which is described below:
 
-.. parsed-literal:
+.. parsed-literal::
 
   *module-member*:
     *requires-declaration*