Fix typo (#1161)

Signed-off-by: David Florness <david@florness.com>

changelogs/client_server/newsfragments/1161.clarification

@@ -0,0 +1 @@
+Fix various typos throughout the specification.

content/client-server-api/modules/end_to_end_encryption.md

@@ -1220,7 +1220,7 @@ replace it with the new key based on the key metadata as follows:
     keep the key that has `is_verified` set to `true`;
 -   if they have the same values for `is_verified`, then it will keep
     the key with a lower `first_message_index`;
--   and finally, is `is_verified` and `first_message_index` are equal,
+-   and finally, if `is_verified` and `first_message_index` are equal,
     then it will keep the key with a lower `forwarded_count`.
 
 ###### Recovery key