Merge branch 'gsell-master-patch-24957' into 'master'

Update Manual.asciidoc

See merge request OPAL/documentation/manual!140

Manual.asciidoc

@@ -35,7 +35,7 @@ endif::[]
 :sectnums!:
 == Preliminary note
 
-This is the manual for _OPAL_ {OPAL_version}. Odd minor version numbers identify
+This is the manual for _OPAL_ {OPAL_version}. Versions with the postfix `-dev` identify 
 development versions. Use these versions only if you know what you are
 doing!