docs: Fix update-spelling_wordlist.sh to run command on spelling errors
docs: Fix update-spelling_wordlist.sh to run command on spelling errors

When spelling mistakes are detected during documentation builds,
check-build.sh suggests running update-spelling_wordlist.sh if the words
are false positives and should be added to the list of exceptions.

The command to run is generated from the entries in the files resulting
from the spell check. But when generating this command, the code assumes
that all such files are directly under _build/spelling/. This is not the
case: they may be in subdirectories instead. If this happens, we fail to
retrieve the entries and to generate the suggested
update-spelling_wordlist.sh command properly.

Fix the issue by searching for all files under _build/spelling/ and
passing them to the pipeline.

Note: We have another "find" command just above and could maybe
consolidate the two somehow; but I did not find any obvious solution
that would escape correctly all spaces in filenames (without using
-print0/-0) and avoid getting some additional warnings from bash (when
storing the result of "find . ... -print0" into a temporary variable).
Let's not overthink this, looking for these files is very fast anyway.

Signed-off-by: Quentin Monnet <d6b8e48afb2534b213e391cab43016505747a234@isovalent.com>

cilium/cilium,cilium/cilium,michi-covalent/cilium,cilium/cilium,michi-covalent/cilium,cilium/cilium,michi-covalent/cilium,cilium/cilium,michi-covalent/cilium,michi-covalent/cilium