Currently, the example uses `@v.0.1.0` version of this package,
and `@master` of get-pr-commits. This is obviously wrong, since
v.0.1.0 is not working with the parameters in the example.

Fix the example using last released versions, and fix some typos
while we're at it.

README.md: update versions, fix typos

In my previous PR #1
I made a mistake of using `v1.0.0` instead of `v0.1.0` in one place. This PR fixes that.

PS can you please enable "Issues" for this repo? I want to report a problem but can't;
thus I am reporting it below.

-----

-- there is a
tag 'v1' in this repo (https://github.com/tim-actions/commit-message-checker-with-regex/releases/tag/v1)
which I think needs to be removed as the latest version is v0.3.1 and v1 > v0,
so dependabot suggest to update from v0.3.1 to v1 which is obviously wrong.

To fix this, `v1` tag need to be removed.

Alternatively, you can release say v1.1 or so and that will fix the issue
(an update to README.md is required).

README.md: fix version

Change Node from 12 to 16

Fixes #13 - set-output command is deprecated, and has been for quite
some time. Guidance was to update `@actions/core` to v1.10.0 or greater.

[fix] Update @actions/core to v1.10.0