Allow override of parachain pallet ID and authorize_upgrade call ID

[Kailai-Wang]

resolves #11

This PR adds two extra envs to allow override of parachain pallet ID and authorize_upgrade call ID

[chevdor]

This project does not use the readme.md directly. The source is actually README_src.adoc and the md is generated. You do not need to bother about the generation itself though but could you please move your doc to the .adoc file ?

The syntax is almost identlical to what you have besides the url which should be http://example.com[some text] instead of [some text](http://example.com)

[Kailai-Wang]

Thanks @chevdor
I reverted README.md and moved the document to examples/05_build_opts.yml

[chevdor]

We cannot do that: the examples/05_build_opts.yml should be a valid yaml file.

Ideally, what we should do is create a new example, include it to the adoc and add your comments in the adoc file.
I would then merge it and regenerate the readme.

[chevdor]

To add an example, you may edit this file:
https://raw.githubusercontent.com/chevdor/srtool-actions/master/examples/index.adoc

to include the new example, and you can add comments in the adoc file.

[Kailai-Wang]

sorry I didn't know that.

I tried to restructure the docs a bit according to your suggestions, please also feel free to edit directly if needed :)

I was not sure if I should include the parachain-overrides.adoc in the index.adoc or README_src.adoc, but I chose the latter eventually..

[chevdor]

Thank you very much for your efforts @Kailai-Wang. I can take it from here.
Note that the doc currently is erroneous as it suggests v0.4.0 contains your overrides.
I will fix that.

[Kailai-Wang]

Thanks. I'm sure I'll do it better next time 🚀