Add info how to install locally

[mesqueeb]

Fixes #2720

This PR contains:

• bugfix
• feature
• refactor
• documentation
• other

Are tests included?

• yes (bugfixes and features will not be merged without tests)
• no

Breaking Changes?

• yes (breaking changes will not be merged unless absolutely necessary)
• no

List any relevant issue numbers:

Description

Fixes #2720

[codecov]

Codecov Report

Merging #2995 into master will decrease coverage by 0.87%.
The diff coverage is n/a.

@@            Coverage Diff            @@
##           master   #2995      +/-   ##
=========================================
- Coverage   88.68%   87.8%   -0.88%     
=========================================
  Files         165     166       +1     
  Lines        5708    5641      -67     
  Branches     1743    1720      -23     
=========================================
- Hits         5062    4953     -109     
- Misses        388     412      +24     
- Partials      258     276      +18

Impacted Files	Coverage Δ
src/utils/renderNamePattern.ts	60% <0%> (-40%)	⬇️
src/utils/relativeId.ts	83.33% <0%> (-16.67%)	⬇️
src/utils/addons.ts	86.66% <0%> (-13.34%)	⬇️
src/ast/nodes/Import.ts	93.18% <0%> (-6.82%)	⬇️
src/utils/transform.ts	90.12% <0%> (-4.69%)	⬇️
src/utils/pluginDriver.ts	82.67% <0%> (-4.5%)	⬇️
src/ModuleLoader.ts	94.08% <0%> (-3.3%)	⬇️
src/Chunk.ts	91.18% <0%> (-1.25%)	⬇️
src/ast/variables/ExportDefaultVariable.ts	88.23% <0%> (-0.96%)	⬇️
src/ast/nodes/SequenceExpression.ts	89.28% <0%> (-0.72%)	⬇️
... and 38 more

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[mesqueeb]

@TrySound
I have updated the branch to reflect your feedback!
Kindly review and advise. ;)

[mesqueeb]

@lukastaegert @tivac @TrySound
I have updated the PR with npx instead of npm run