Rename to 'gl-sak' and start documenting

fish → gl-sak

 #!/usr/bin/env python3
 
+"""gl-sak: GitLab Swiss Army Knife.
+
+A general-purpose GitLab tool for batch access to and manipulation of
+entities (issues, labels, milestones, etc) in a GitLab project.
+"""
+
 # To get started:
 # 
 #   $ git clone git@gitlab.com:python-gitlab/python-gitlab.git
@@ -16,9 +22,15 @@ import argparse
 def main():
     # Set up options and arguments
     arg_parser = argparse.ArgumentParser(
-        description="Do some things with the GitLab API",
-        epilog="What we do in the shadows, after the main help text.")
-    arg_parser.add_argument('-t', '--access-token')
+        prog="gl-sak", 
+        description=__doc__,
+        # https://docs.python.org/3/library/argparse.html#formatter-class
+        # says more about this next argument.  Another possible value
+        # here would be RawDescriptionHelpFormatter.
+        formatter_class=argparse.RawTextHelpFormatter)
+    arg_parser.add_argument(
+        '-t', '--access-token',
+        help="The GitLab access token to use for this operation")
     args = arg_parser.parse_args()
 
     # Set up the GitLab instance.