Add links to SSH/GPG usage examples

libagent/gpg/__init__.py

@@ -253,7 +253,9 @@ def run_agent(device_type):
 
 def main(device_type):
     """Parse command-line arguments."""
-    parser = argparse.ArgumentParser()
+    epilog = ('See https://github.com/romanz/trezor-agent/blob/master/'
+              'doc/README-GPG.md for usage examples.')
+    parser = argparse.ArgumentParser(epilog=epilog)
 
     agent_package = device_type.package_name()
     resources_map = {r.key: r for r in pkg_resources.require(agent_package)}

libagent/ssh/__init__.py

@@ -65,7 +65,10 @@ def _to_unicode(s):
 
 def create_agent_parser(device_type):
     """Create an ArgumentParser for this tool."""
-    p = configargparse.ArgParser(default_config_files=['~/.ssh/agent.config'])
+    epilog = ('See https://github.com/romanz/trezor-agent/blob/master/'
+              'doc/README-SSH.md for usage examples.')
+    p = configargparse.ArgParser(default_config_files=['~/.ssh/agent.config'],
+                                 epilog=epilog)
     p.add_argument('-v', '--verbose', default=0, action='count')
 
     agent_package = device_type.package_name()