[community standards] Clear up branches coast

[thogar-computer]

Intro

There is a checklist of items that GitHub has picked as 'good practice' for Open Source projects to follow;

https://github.com/British-Oceanographic-Data-Centre/COAsT/community

we have some of these already and it would be good to get a full house

User Story

As a contributor, I want to know which branches are current and active, so I can quickly see what needs to be reviewed

Given the COAsT repo is public and open to all
When a new contributor joins
Then they know how many branches are actively being worked on

details

We really need to remove the stable merged branches as currently, we have 62 branches and of which a few still to be used

AC

This ticket is done, when the COAsT repo has all merged branches removed (minus the development branch)

[lukegorman]

i have deleted a lot of branches. Over to MSM to have a look at the stale branches and delete where required :)