actions/create-release#124 adding tag_name to outputs

[takilara]

ref #124
Changes:

• added tag_name to outputs
• added secondary test for a different version
• Updated README.md to include the output

[takilara]

Note! This feature might not be needed for the general public, as it can be solved by using set-output, e.g.
run: echo ::set-output name=version::${GITHUB_REF#refs/*/}

I am leaving the pull request here for now in case this is a relevant request. Close it if not desired.

[Pierstoval]

I feel like it's way more convenient to use this PR if you just want the tag v0.1.0 instead of having to execute this echo ::set-output ... command by youself.

I was about to create PR for this feature to simplify using the tag 😉