docs: describe required Token Permissions for pipe-cd/actions-gh-release

[abacchilb]

What would you like to be added:

In the https://github.com/pipe-cd/actions-gh-release/blob/main/README.md - document what permissions the GITHUB_TOKEN needs.

Why is this needed:

Github has updated their default token posture to only allow the token to read and not write. So now you need to set permissions above that in each job. It will be helpful to explicitly tell users what permissions are needed. ex:

permissions:
  contents: read
  issues: write
  pull-requests: write
  statuses: read
  checks: read

[khanhtc1202]

Hi @abacchilb, sorry for the late response 🙏 . Would you like to submit a PR for docs fix 😄

[abhinavs1920]

@khanhtc1202 can I take this up and add a PR for this, I have read the readme and github's token policy. 😄

[t-kikuc]

@abhinavs1920 Hey, I assigned you. Thank you!

[abhinavs1920]

@t-kikuc @khanhtc1202 Please check the PR I have created which will resolve the issue.

Thankss!!