Resolve main/master branches according to latest template

[KateSakharova]

Description of feature

1. .github/PULL_REQUEST_TEMPLATE.md has master

Learn more about contributing: [CONTRIBUTING.md](https://github.com/nf-core/seqsubmit/tree/main/.github/CONTRIBUTING.md)
to
Learn more about contributing: [CONTRIBUTING.md](https://github.com/nf-core/seqsubmit/tree/master/docs/CONTRIBUTING.md)

- [ ] If you've added a new tool - have you followed the pipeline conventions in the [contribution docs](https://github.com/nf-core/seqsubmit/tree/main/.github/CONTRIBUTING.md)
to
- [ ] If you've added a new tool - have you followed the pipeline conventions in the [contribution docs](https://github.com/nf-core/seqsubmit/tree/master/docs/CONTRIBUTING.md)

2. subworkflows/local/utils_nfcore_seqsubmit_pipeline/main.nf

 https://github.com/nf-core/seqsubmit/blob/main/CITATIONS.md
to
    https://github.com/nf-core/seqsubmit/blob/master/CITATIONS.md

3. Check can we delete in .nf-core.yml lines Initial release #72 (comment)

  files_unchanged:
    - .github/PULL_REQUEST_TEMPLATE.md