Update event_listeners.rst

[ifeoluwafavour]

Documentation for Event Listeners component #215

[RCheesley]

Thanks so much for the great work on this PR @ifeoluwafavour - it's fantastic to see these docs coming over to the new documentation!

I've left a bunch of suggestions to fix the many Vale suggestions from Reviewdog, have a look and see what you think!

[ifeoluwafavour]

Hello @RCheesley
Thank you for your kind words. I'm learning a lot!

I have applied the suggested changes. To accurately follow the external link syntax, I created a pull request to include Symfony's docs event subscribers link file to the link folder:
https://github.com/mautic/developer-documentation-new/pull/221/checks

[RCheesley]

Some tweaks to fix the heading nestings, and I've asked the devs to do a technical review, too! Thanks for the great work so far!

[ifeoluwafavour]

Thank you @RCheesley for your guidance so far!

I changed 'Subscribers' to 'Event Sunscribers' in the recent commit. Is it a better heading name?

[RCheesley]

Looks like just a vale fix and we're good to go! 🚀 Thanks @ifeoluwafavour for all the hard work here!

[RCheesley]

I think this is GTG but we'll need to forward-port it to other branches.

[adiati98]

I think this is GTG but we'll need to forward-port it to other branches.

We only have 5.x branch for this repo at the moment.