Update Nextflow installation link in pipeline template

[ErikDanielsson]

Updated changed link for Nextflow installation from nf-co.re/usage/installation to https://www.nextflow.io/docs/latest/getstarted.html#installation as suggested in #1201. Updated nf-core bump-version to check for references to nf-co.re/usage/installation and replace them with the Nextflow link.

PR checklist

• This comment contains a description of changes (with reason)
• CHANGELOG.md is updated
• If you've fixed a bug or added code that should be tested, add tests!
• Documentation in docs is updated

[codecov]

Codecov Report

Merging #1210 (59d2d80) into dev (5342803) will decrease coverage by 0.05%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##              dev    #1210      +/-   ##
==========================================
- Coverage   69.45%   69.40%   -0.06%     
==========================================
  Files          49       49              
  Lines        5419     5419              
==========================================
- Hits         3764     3761       -3     
- Misses       1655     1658       +3     

Impacted Files	Coverage Δ
nf_core/bump_version.py	91.52% <ø> (ø)
nf_core/lint/readme.py	68.96% <0.00%> (-10.35%)	⬇️

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[drpatelh]

🚀