[bug#51779] [PATCH] Add phonesim 1.21

[Josselin Poiret]

Hello Demis,

About the ChangeLog style, it is documented at [1], and it mostly
concerns the contents of the commit message.  In the case of this patch,
I think it should be

--8<---------------cut here---------------start------------->8---
gnu: Add phonesim.

* gnu/packages/telephony.scm (phonesim): Add new variable.
--8<---------------cut here---------------end--------------->8---

You can take a look at the complete commit messages in the git log to
get a feel for what needs to be included in them.

As for the patch, it looks good to me, but I'm no expert yet.  Glad to
see your first contribution though!

[1] https://www.gnu.org/prep/standards/html_node/Change-Logs.html

Best,
Josselin Poiret