Updated Plugin migration to QGIS 3 (markdown)

Plugin-migration-to-QGIS-3.md

@@ -7,3 +7,19 @@ Among the necessary info:
 * QGIS3 compat module (so 3.x plugins will also work on 2.18) from Matthias.
 
 When completed, we need to put out a call for plugin authors to start porting.
+
+## Minimal info
+
+- run scripts/2to3 (https://github.com/qgis/QGIS/blob/master/scripts/2to3) on your plugin
+- have a good look at: https://qgis.org/api/api_break.html
+- make sure you do python3 and QT5 !
+- tweak and fix until it works :-)
+
+it was more work then I hoped, but after setting
+
+```
+qgisMinimumVersion=2.99
+qgisMaximumVersion=3.0 (optional)
+```
+
+in metadata you should see your plugin in QGIS 2.99 and up