ff72078095Document return type of `sign` method. (Thibaut Le Guilly) Pull request description: Small thing but I had to look up the code to see what the returned boolean was about, thought it might be good to have in the docs. ### Description Documents the meaning of the returned value on the wallet `sign` method. I've just edited from github so skipped all the checks if that's not ok maybe someone else can update it properly. ACKs for top commit: w0xlt: ACK https://github.com/bitcoindevkit/bdk/pull/834/commits/ff720780950e010cb13af7def1d2226841ca3f97 notmandatory: ACKff72078095Tree-SHA512: e0dd52a0af663b88d3fe0a20cb2909b9ba00bcf4f224b4f87cfd53fee0a199a01679dc5cd74aeb440326dfc52d45fa887534138d25df6fa1c8a38678be23204e