Tests: add pointer to cover script which runs them.

devel/cover

@@ -1,6 +1,6 @@
 #!/bin/sh
 #
-# Coverage and unit tests!
+# Build a coverage-enabled darkhttpd, run unit tests and calculate coverage.
 #
 cd $(dirname $0)
 DIR=tmp.httpd.tests

devel/test.py

@@ -1,4 +1,5 @@
 #!/usr/bin/env python
+# This is run by the "cover" script.
 import unittest
 import socket
 import signal

devel/test_forward.py

@@ -1,4 +1,5 @@
 #!/usr/bin/env python
+# This is run by the "cover" script.
 import unittest
 from test import TestHelper, Conn, parse
 

devel/test_server_id.py

@@ -1,4 +1,5 @@
 #!/usr/bin/env python
+# This is run by the "cover" script.
 import unittest
 from test import TestHelper, Conn, parse