[doc][tools] Add spell checking scripts

[fernape]

Summary

Add two small scripts to do spell checking in .po files.

When working with Weblate, the web browser provides some spell checking with
visual hints for every translation entry.

These scripts provide spell checking for the whole file showing the faulting
words in context.

Relies on msgexec(1) and aspell(1) from devel/gettext-tools and
textproc/aspell.

Test Plan

It can be tested with:

./po_spellcheck.sh ../documentation/content/es/articles/bsdl-gpl/_index.po es

[carlavilla]

Can you please add the license copyright in the header?

[fernape]

• Add license.
  
  2-clause BSD license[1]
  
  [1] https://opensource.org/licenses/BSD-2-Clause

[fernape]

In D32465#732362, @carlavilla wrote:

Can you please add the license copyright in the header?

Done.

Thanks!

[carlavilla]

Nice, thanks, for me it’s ok.
Can we wait to @dbaio?

[fernape]

In D32465#732371, @carlavilla wrote:

Nice, thanks, for me it’s ok.
Can we wait to @dbaio?

Absolutely. Thanks for the review!

[dbaio]

Good idea Fernando.

Just a few points to check.

tools/po_check_entry.sh

30–31

Improve text here, example from documentation/Makefile:

${COMMAND} not found, please run 'pkg install aspell $your_lang-aspell

And use other exit code number, other than 0.

38

exit 1 is better

tools/po_spellcheck.sh

30–31

Improve text here, example from documentation/Makefile:

${COMMAND} not found, please run 'pkg install docproj

I let docproj because it includes po4a, which requires gettext-tools.

And use other exit code number, other than 0.

42

exit 1 is better

50–51

You can use dirname "$0" to get the full directory that po_spellcheck.sh was executed from, so we can call it from anywhere.

[fernape]

Address dbaio@ comments:

• Use exit 1
• Improve error messages
• Allow invocation from everywhere

[fernape]

Thanks for the suggestions.