Add options to run command on "else" branch of install

[bahmutov]

For example if there is not JSON message, then allow running specific command

$(npm bin)/commit-message-install --else "echo nothing to do"

[bahmutov]

Version 1.6.0 has been published to NPM. The full release note can be found at commit-message-install/releases/tag/v1.6.0.

Tip: safely upgrade dependency commit-message-install in your project using next-update