docs: python bindings howto

* Added section on revoking UIDs.

lang/python/docs/GPGMEpythonHOWTOen.org

@@ -1214,6 +1214,12 @@
    :CUSTOM_ID: keygen-uids
    :END:
 
+
+*** Adding User IDs
+    :PROPERTIES:
+    :CUSTOM_ID: keygen-uids-add
+    :END:
+
     By comparison to creating primary keys and subkeys, adding a new
     user ID to an existing key is much simpler.  The method used to do
     this is =key_add_uid= and the only arguments it takes are for the
@@ -1248,6 +1254,28 @@
     #+end_src
 
 
+*** Revokinging User IDs
+    :PROPERTIES:
+    :CUSTOM_ID: keygen-uids-revoke
+    :END:
+
+    Revoking a user ID is a fairly similar process, except that it
+    uses the =key_revoke_uid= method.
+
+    #+begin_src python
+      import gpg
+
+      c = gpg.Context()
+      c.home_dir = "~/.gnupg-dm"
+
+      dmfpr = "177B7C25DB99745EE2EE13ED026D2F19E99E63AA"
+      key = c.get_key(dmfpr, secret=True)
+      uid = "Danger Mouse <danger.mouse@secret.example.net>"
+
+      c.key_revoke_uid(key, uid)
+    #+end_src
+
+
 ** Key certification
    :PROPERTIES:
    :CUSTOM_ID: key-sign