Add new categories to instance list

[garridinsi]

Hi!

Here an Mastodon instance admin. We recently opted to appear on the server list and our submission got accepted. On the time of thinking about the categories that apply to our server, we found that some that for us seem essential are missing.

Our instance (social.ferrocarril.net), is based on people that love trains, railroads and related, also on model and scale railroads.

We think that some categories such as Hobbies, Culture or Geek should be added to the server list, making the list more plural and wide, to not group this type of instances on General.

Thanks

[kergozh]

We are in the same situation. I think new categories would be great both for server and new users.

[trankten]

Hello. I also agree. It would be amazing to include one for "Geek culture".

Thank you.

[garridinsi]

I've created a pull request #286. I've also observed that #259 is requesting to add Science