Fix broken nodocs

This commit fixes all references in the codebase missing a trailing :,
which causes the nodoc not to actually work :) [skip ci]

actionpack/lib/action_dispatch/middleware/flash.rb

@@ -73,7 +73,7 @@ def commit_flash # :nodoc:
         end
       end
 
-      def reset_session # :nodoc
+      def reset_session # :nodoc:
         super
         self.flash = nil
       end

activerecord/lib/active_record/associations.rb

@@ -241,7 +241,7 @@ def association(name) #:nodoc:
       association
     end
 
-    def association_cached?(name) # :nodoc
+    def association_cached?(name) # :nodoc:
       @association_cache.key?(name)
     end
 

activerecord/lib/active_record/attribute_methods/read.rb

@@ -69,7 +69,7 @@ def read_attribute(attr_name, &block)
       if defined?(JRUBY_VERSION)
         # This form is significantly faster on JRuby, and this is one of our biggest hotspots.
         # https://github.com/jruby/jruby/pull/2562
-        def _read_attribute(attr_name, &block) # :nodoc
+        def _read_attribute(attr_name, &block) # :nodoc:
           @attributes.fetch_value(attr_name.to_s, &block)
         end
       else