Add more specific descriptions for the individual features

de.prob2.disprover.feature/feature.xml

@@ -7,6 +7,8 @@
       plugin="de.prob.eventb.disprover.ui">
 
    <description url="https://prob.hhu.de/w/">
+Allows using ProB as a (dis)prover while proving POs.
+
 ProB is an animator and model checker for the B-Method. It allows
 fully automatic animation of many B specifications, and can be
 used to systematically check a specification for errors.

de.prob2.feature/feature.xml

@@ -7,6 +7,8 @@
       plugin="de.prob.ui">
 
    <description url="https://prob.hhu.de/w/">
+ProB animator plug-in for Rodin. Also includes BMotion Studio.
+
 ProB is an animator and model checker for the B-Method. It allows
 fully automatic animation of many B specifications, and can be
 used to systematically check a specification for errors.

de.prob2.symbolic.feature/feature.xml

@@ -7,6 +7,9 @@
       plugin="de.prob.symbolic">
 
    <description url="https://prob.hhu.de/w/">
+Allows marking constants as symbolic so that the ProB animator will not
+evaluate them eagerly.
+
 ProB is an animator and model checker for the B-Method. It allows
 fully automatic animation of many B specifications, and can be
 used to systematically check a specification for errors.