Add documentation and #filtered?

lib/metasploit/framework/credential_collection.rb

@@ -122,6 +122,13 @@ def empty?
       prepended_creds.empty? && !has_privates?
     end
 
+    # Returns true when a filter is defined
+    #
+    # @return [Boolean]
+    def filtered?
+      !self.filter.nil?
+    end
+
     # Returns true when there are any private values set
     #
     # @return [Boolean]

lib/msf/core/auxiliary/auth_brute.rb

@@ -46,6 +46,13 @@ def initialize(info = {})
     ], Auxiliary::AuthBrute)
   end
 
+  # Build a new CredentialCollection instance configured based on the datastore options. Any options passed in will take
+  # precedence over the datastore. Usernames and passwords will be prepended to the credential collection if their
+  # respective datastore options are configured appropriately. Finally the resulting CredentialCollection will be
+  # configured to perform any necessary filtering per the DB_SKIP_EXISTING option.
+  #
+  # @param [Hash] opts the options with which to build the CredentialCollection instance
+  # @return [Metasploit::Framework::CredentialCollection] the built CredentialCollection
   def build_credential_collection(opts)
     cred_collection = Metasploit::Framework::CredentialCollection.new({
       blank_passwords: datastore['BLANK_PASSWORDS'],