minor fix for apostrophes

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@8831 71c3de6d-444a-0410-be80-ed276b4c234a

core/src/main/resources/hudson/scm/SubversionSCM/config.properties

 updateDescription=\
-  If checked, Hudson will use 'svn update' whenever possible, making the build faster. \
+  If checked, Hudson will use ''svn update'' whenever possible, making the build faster. \
   But this causes the artifacts from the previous build to remain when a new build starts.