Added SUPPORT.md file with slack info ✈️

no issue

- Adds a guide for how to get support 📖
- Committed at 38000ft ✈️

.github/SUPPORT.md

@@ -0,0 +1,28 @@
+# How to get support for Ghost 👨‍👩‍👧‍👦
+
+If you are looking for help, support or the answer to a question, please use **[slack](https://ghost.org/slack)**.
+
+Please **_do not_** raise an issue on GitHub.
+
+We have a **#help** channel in our **[slack](https://slack.ghost.org/)** team where you can get quick answers,
+help with debugging weird issues, and general help with any aspect of Ghost.
+
+Our extensive **documentation** can be found at https://docs.ghost.org.
+
+Please go to https://slack.ghost.org and request an invite to join our community.
+Invites are sent instantly and this is the fastest way to get help.
+
+Issues which are not bug reports will be closed.
+
+## Using Ghost(Pro)?
+
+**Ghost(Pro)** users have access to email support via the support at ghost dot org address.
+
+## Why not GitHub?
+
+GitHub is our office, it's the place where our development team does its work. We use the issue list
+to keep track of bugs and the features that we are working on. We do this openly for transparency.
+
+On slack, you can leverage the knowledge of our wider community to get help with any problems you are
+having with Ghost. Please keep in mind that Ghost is FLOSS, and free support is provided by the goodwill
+of our wonderful community members.