:bug: Documentation typos

[lmrb-1968]

There are some documentation issues.

• Under Add a step calling the action, the pattern specified .github/*.yml is not correct. The correct one is .github/workflows/*.yml

• The version tag is 2.0 in the examples, should be updated with the latest version.

• --fail=severity:critical does not work. --fail=critical is the right syntax.

• The example at the end could use multi-line command using the "block chomp & strip" >- YAML operator, for clarity:

  - name: Xygeni-Scanner
    uses: xygeni/xygeni-action@v2.1
    id: Xygeni-Scanner
    with:
      token: ${{ secrets.XYGENI_TOKEN }}
      command: >-
         scan -n ${{ github.repository }} -d ${{ github.repository }}
              --run=secrets,iac --fail-on=critical

• Probably a final note recommending action version pinning (using the SHA for the action tag) should be recommended, to follow Xygeni's recommendation for pinning action versions. Proposed text:

NOTE: You may use pinned versions for the action, using the immutable commit SHA instead of version numbers, as specified in [Pin actions to full length commit SHA](https://docs.github.com/en/actions/security-guides/security-hardening-for-github-actions#using-third-party-actions).

Please compare this with the ascidoc version in Xygeni documentation (in development environment) with the fixed issues.

[lmrb-1968]

Done in Added starter workflow and updated Readme #25