message: doc: Update labels in CONTRIBUTING.md
  Add `build' label.
  Make labels lowercase.
  Split long labels.
diff: @@ -79,25 +79,26 @@ about Git.
  The title of the pull request should be prefixed by the component or area that
  the pull request affects. Valid areas as:
  - - *Consensus* for changes to consensus critical code
  - - *Doc* for changes to the documentation
  - - *Qt* for changes to bitcoin-qt
  - - *Log* Changes to log messages
  - - *Mining* for changes to the mining code
  - - *Net* or *P2P* for changes to the peer-to-peer network code
  - - *Refactor* for structural changes that do not change behavior
  - - *RPC/REST/ZMQ* for changes to the RPC, REST or ZMQ APIs
  - - *Scripts and tools* for changes to the scripts and tools
  - - *Test* for changes to the bitcoin unit tests or QA tests
  - - *Utils and libraries* for changes to the utils and libraries
  - - *Wallet* for changes to the wallet code
  + - `consensus` for changes to consensus critical code
  + - `doc` for changes to the documentation
  + - `qt` or `gui` for changes to bitcoin-qt
  + - `log` for changes to log messages
  + - `mining` for changes to the mining code
  + - `net` or `p2p` for changes to the peer-to-peer network code
  + - `refactor` for structural changes that do not change behavior
  + - `rpc`, `rest` or `zmq` for changes to the RPC, REST or ZMQ APIs
  + - `script` for changes to the scripts and tools
  + - `test` for changes to the bitcoin unit tests or QA tests
  + - `util` or `lib` for changes to the utils or libraries
  + - `wallet` for changes to the wallet code
  + - `build` for changes to the GNU Autotools, reproducible builds or CI code
  Examples:
  - Consensus: Add new opcode for BIP-XXXX OP_CHECKAWESOMESIG
  - Net: Automatically create hidden service, listen on Tor
  - Qt: Add feed bump button
  - Log: Fix typo in log message
  + consensus: Add new opcode for BIP-XXXX OP_CHECKAWESOMESIG
  + net: Automatically create hidden service, listen on Tor
  + qt: Add feed bump button
  + log: Fix typo in log message
  Note that translations should not be submitted as pull requests, please see
  [Translation Process](https://github.com/bitcoin/bitcoin/blob/master/doc/translation_process.md)
  