Github actions secrets correction in documentation

[paulcjh]

Currently in the main sync docs here the method used for using github secrets doesn't work. It requires the addition of $ at the start to yield the secret:

Old

- uses: readmeio/rdme@RDME_VERSION
  with:
    rdme: openapi [path-to-file.json] --key={{ secrets.README_API_KEY }} --id={{ secrets.README_API_DEFINITION_ID }}

New

- uses: readmeio/rdme@RDME_VERSION
  with:
    rdme: openapi [path-to-file.json] --key=${{ secrets.README_API_KEY }} --id=${{ secrets.README_API_DEFINITION_ID }}

[kanadgupta]

Yikes, thanks for the catch @paulcjh! Fixed in #471 and the changes are now live: https://docs.readme.com/docs/rdme#example-using-github-secrets

[paulcjh]

Thanks! @kanadgupta