doc: Add manual page generation for bitcoin-util

doc: Add manual page generation for bitcoin-util

- Add `-version` option to `bitcoin-util`
- Add `bitcoin-util` call to `gen-manpages.sh`
- Add stub manual page `bitcoin-util.1`
- Add install of `bitcoin-util.1` to build system

情報元 - doc: Add manual page generation for bitcoin-util · bitcoin/[email protected] · GitHub