Provide description for parameters

A few parameters lacked descriptions. These were added. Architectures do
not have a description yet.

Jenkinsfile

@@ -81,10 +81,10 @@ pipeline {
         booleanParam(name: 'x86_generic', defaultValue: true, description: '')
         booleanParam(name: 'x86_geode', defaultValue: true, description: '')
         booleanParam(name: 'x86_64', defaultValue: true, description: '')
-        booleanParam(name: 'verbose', defaultValue: false, description: '')
-        booleanParam(name: 'make_clean', defaultValue: false, description: '' )
-        booleanParam(name: 'clean_workspace', defaultValue: false, description: '' )
-        choice(name: 'broken', choices: '1\n0', description: '')
+        booleanParam(name: 'verbose', defaultValue: false, description: 'build with -j1 and V=s for debugging build errors')
+        booleanParam(name: 'make_clean', defaultValue: false, description: 'execute make clean before building each architecture' )
+        booleanParam(name: 'clean_workspace', defaultValue: false, description: 'delete all files in workspace before building' )
+        choice(name: 'broken', choices: '1\n0', description: 'wether to build broken targets or not')
         string(defaultValue: "refs/tags/v2017.1.7", name: 'gluon', description: 'gluon release tag')
         string(defaultValue: "*/master", name: 'site', description: 'site release tag, branch or commit')
     }