Updated Plugin migration to QGIS 3 (markdown)

Plugin-migration-to-QGIS-3.md

@@ -1,12 +1,4 @@
-Please add here a guide for the migration, with a list of useful resources.
-
-Among the necessary info:
-* API breaks documentation
-* Python API docs from Denis
-* From2to3 script from Jürgen
-* 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.
+QGIS 3 has entered code freeze. It's therefore time to port your plugin.
 
 While you are porting/rewriting your plugin, think about using QGIS native widgets. For instance, if you need a combobox with layers, use a `QgsMapLayerComboBox` instead of a `QComboBox`. There is also `QgsFieldComboBox` if you need to pick a field in a vector layer. The full list of widgets is here https://qgis.org/api/group__gui.html
 
@@ -22,10 +14,17 @@ Also think about using the Processing framework. Your plugin can become its own
 - make sure you do python3 and QT5 !
 - tweak and fix until it works :-)
 
-it was more work then I hoped, but after setting
+It was more work then I hoped, but after setting
 
 ```
 qgisMinimumVersion=3.0
 ```
 
 in metadata you should see your plugin in QGIS 2.99 and up (*note: if your QGIS 2.99 build is older than 4.01.2018, you need to either update it or set qgisMinimumVersion=2.99 and qgisMaximumVersion=3.98, as there was an important change 3.01.2018 17:09 UTC: https://github.com/qgis/QGIS/pull/5904*)
+
+
+More info (to be added):
+* Python API docs from Denis
+* 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.