introduce BRANCHES info

BRANCHES.md

@@ -0,0 +1,43 @@
+Installing from branches
+========================
+
+[⬅️ Go back to main README](README.md)
+
+> ⚠️ **Warning**: Living on the edge? Great, read on!
+> If not: Please use the `main` branch and leave this page!
+
+These scripts are developed in a [git](https://git-scm.com/) repository.
+Development and experimental branches are used to provide early access
+for specific changes. You can install scripts from these branches
+for testing.
+
+## Install single script
+
+To install a single script from `next` branch:
+
+    $ScriptInstallUpdate script-name "url-suffix=?h=next";
+
+## Switch existing script
+
+Alternatively switch an existing script to update from `next` branch:
+
+    /system/script/set comment="url-suffix=?h=next" script-name;
+    $ScriptInstallUpdate;
+
+## Switch installation
+
+Last but not least - to switch the complete installation to the `next`
+branch edit `global-config-overlay` and add:
+
+    :global ScriptUpdatesUrlSuffix "?h=next";
+
+... then reload the configuration and update:
+
+    /system/script/run global-config;
+    $ScriptInstallUpdate;
+
+> ℹ️ **Info**: Replace `next` with *whatever* to use another specific branch.
+
+---
+[⬅️ Go back to main README](README.md)  
+[⬆️ Go back to top](#top)