Update documentation to include how-to information on the egguy add-on

[muppet3000]

As per the discussions on #16 the documentation should be updated for people that want to use the egguy HA add-on to run grott: https://github.com/egguy/grott-home-assistant-add-on/tree/main

[BobC76]

FWIW I used this and it worked a treat. Since I plan on not ever having HA offline any more or less than some other server, was no particular need to host Grott somewhere else. I found the instructions on installing the egguy grott fine so I took the liberty of making a proposed change to the docs mainly as the existing instructions over there are simple enough as is. #66

What would be interesting to know is are there material differences running the egguy HA grott plug in vs standalone grott and/or the egguy HA integration surfacing entities in MQTT vs the muppet3000 grott integration?

[muppet3000]

There is literally nothing different, the egguy addon just bundles up grott and allows you to run it as a home-assistant add-on. Not everyone runs home assistant OS and therefore not everyone has the luxury of using 'add-ons' (they're only supported in certain flavours of Home Assistant) hence why the documentation never mentioned it originally. I admit that for people that can use add-ons it's a quick and easy to use solution to the problem.

Thank you for the PR, I've just merged it.

[muppet3000]

Note - I'll keep this ticket open in case anything else comes up with regards to the egguy addon