Add TM4E source feature group

The TM4E sources were being generated but not added to the simultaneous
releases Update Site. See https://github.com/eclipse/tm4e/issues/252

Having them available on it will ease the debugging of TM4E code when
you have this Update Site on a target platform without needing to add
the corresponding TM4E Update Site and version used to build the
Simultaneous Release.

Change-Id: I22830368c2222cf4d83b4240de07239740a5b691
Signed-off-by: Martin D'Aloia <martindaloia@gmail.com>
diff --git a/tm4e.aggrcon b/tm4e.aggrcon
index b72f590..ae15abd 100644
--- a/tm4e.aggrcon
+++ b/tm4e.aggrcon
@@ -4,6 +4,7 @@
     <features name="org.eclipse.tm4e.feature.feature.group" versionRange="[0.4.1.202008270629]">
       <categories href="simrel.aggr#//@customCategories[identifier='Programming%20Languages']"/>
     </features>
+    <features name="org.eclipse.tm4e.feature.source.feature.group" versionRange="[0.4.1.202008270629]"/>
   </repositories>
   <contacts href="simrel.aggr#//@contacts[email='mistria@redhat.com']"/>
   <contacts href="simrel.aggr#//@contacts[email='angelozerr@gmail.com']"/>