Explicitly mention signed commits/tags in features

Author: Byron

README.md

@@ -99,7 +99,7 @@ Please see _'Development Status'_ for a listing of all crates and their capabili
     * [x] [error line](https://github.com/git/git/blob/master/Documentation/technical/pack-protocol.txt#L28:L28)
     * [x] [V2 additions](https://github.com/git/git/blob/master/Documentation/technical/protocol-v2.txt#L35:L36)
     * [x] [side-band mode](https://github.com/git/git/blob/master/Documentation/technical/pack-protocol.txt#L467:L467)
-  * [ ] `Iterator` for multi-plexed pack lines from `Read`
+  * [ ] PacketLine `Iterator` from `Read`
   * [ ] parse and serialize [capabilities](https://github.com/git/git/blob/master/Documentation/technical/protocol-capabilities.txt#L1:L1)
   * [ ] **Version 1**
     * [ ] [fetch](https://github.com/git/git/blob/master/Documentation/technical/pack-protocol.txt#L157:L157)
@@ -130,6 +130,7 @@ Please see _'Development Status'_ for a listing of all crates and their capabili
 ### git-repository
   * [x] initialize
     * [ ] Proper configuration depending on platform (e.g. ignorecase, filemode, …)
+  * [ ] [Signed commits and tags](https://github.com/Byron/gitoxide/issues/12)
   * [ ] read and write all data types
   * [ ] rev-parsing and ref history
   * [ ] remotes with push and pull