Show binary releases details on resolc-bin GH Pages site (#447)

## Description

For more easily finding the details of the resolc binary releases for
the various supported platforms, the plain JSON information will be
displayed on [resolc-bin](https://github.com/paritytech/resolc-bin)'s
[GitHub Pages website](https://paritytech.github.io/resolc-bin/).

Changes:
* Whenever there is a regular or nightly release:
* The corresponding workflow files will run a script to update
resolc-bin's `index.md` file (new file) with the updated JSON.
* `index.md` will be the file GitHub Pages serves as HTML (by default it
is built with Jekyll and the Markdown is processed by kramdown, hence
the syntax seen in the script).
* Documentation  updates

Thus, this will run on the next nightly release after this PR is merged.

## Resolved Issues

Closes #443

---------

Co-authored-by: xermicus <cyrill@parity.io>

.github/workflows/generate_versions.yml

@@ -47,6 +47,10 @@ jobs:
           cd resolc-bin
           python ../tmp/.github/scripts/json_generator.py ${GITHUB_REPOSITORY} ${{ github.event.release.tag_name }}
 
+          # Update GitHub Pages file with the JSON data.
+          chmod +x ../tmp/.github/scripts/resolc-bin-gh-pages.sh
+          bash ../tmp/.github/scripts/resolc-bin-gh-pages.sh $PWD
+
           echo "${Green}Add new remote with gh app token${NC}"
           git remote set-url origin $(git config remote.origin.url | sed "s/github.com/${APP_NAME}:${TOKEN}@github.com/g")