Update python module docstrings to match the script names

Author: bd1976bris

llvm/utils/dtlto/local.py

@@ -7,7 +7,7 @@
 used for integration tests.
 
 Usage:
-    python dtlto_codegen.py <json_file>
+    python local.py <json_file>
 
 Arguments:
     - <json_file> : JSON file describing the DTLTO jobs.

llvm/utils/dtlto/mock.py

@@ -6,10 +6,10 @@
 perform the backend compilation jobs.
 
 Usage:
-    python mock_distributor.py <input_file1> <input_file2> ... <json_file>
+    python mock.py <input_file1> <input_file2> ... <json_file>
 
 Arguments:
-    - <input_file1>, <input_file2>, ... : Input files to be copied.
+    - <input_file1>, <input_file2>, ...  : Input files to be copied.
     - <json_file>                        : JSON file describing the DTLTO jobs.
 
 The script performs the following: