How to build packages locally: address prior revision comments

[BAMF0]

Page URL

https://documentation.ubuntu.com/project/contributors/bug-fix/build-packages-locally/#

Issue Description

(This is a follow-up issue created based on suggestions from #431)

Currently, the article "How to build packages locally" is missing some additional explanations. These are:

1. Under "Building with sbuild", the article should mention how sbuild needs to build a source package and will run debian/clean. This step might require build-dependencies to be installed and there should be an explanation regarding why --no-clean-source might be used.
   (Reference comment)

2. Under "Building for architecture variants", the suggested method is incorrect and the correct method is actually more complex.
   (Reference comment)