Remove outdated user error description

USER_ERRORS

@@ -9,8 +9,3 @@ Java process ends with SEGFAULT
  - HOW TO FIX: Fix the instrumentation or exclude the class causing the problem
           in the exclusion list (-Ddisl.exclusionList=exclusion.lst command line
           option of DiSL server).
-
-Build failure: java.lang.UnsupportedClassVersionError: ch/usi/dag/disl/utilinstr/tlvinserter/ExtendThread : Unsupported major.minor version 51.0
- - CAUSE: A version 1.7.x JRE is used; this version is not yet supported
- - HOW TO FIX: Use a version 1.6.x JRE instead.
-