books/: Address more instances of sentences beginning with 'Because...'

As was the case with the previous commit, the intention is to avoid
sentence fragments as well as sentences that can be mistaken for them,
since the handbook isn't written in a style that makes use of
subordinate conjunctions.

While touching the relevant files, I also fixed a few issues pointed
out by PauAmma, and reflowed a sentence as a result.

PR: 252519
Submitted by: ceri@
Reviewed by: PauAmma