add: Fix bad metaVar reference in <filepattern> help

Without this patch, "jgit add --help" throws two exceptions
(NoSuchFieldException: metavar_filepattern; MissingResourceException:
Can't find resource for bundle java.util.PropertyResourceBundle, key
metavar_filepattern) instead of printing a usage message, due to a
small typo and a missing declaration.

Change-Id: I4b848b3a8c7b1a49d8b9582809375daa4aca6b50

org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/Add.java

@@ -57,7 +57,7 @@ class Add extends TextBuiltin {
 	@Option(name = "--update", aliases = { "-u" }, usage = "usage_onlyMatchAgainstAlreadyTrackedFiles")
 	private boolean update = false;
 
-	@Argument(required = true, metaVar = "metavar_filepattern", usage = "usage_filesToAddContentFrom")
+	@Argument(required = true, metaVar = "metaVar_filepattern", usage = "usage_filesToAddContentFrom")
 	private List<String> filepatterns = new ArrayList<String>();
 
 	@Override

org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/CLIText.java

@@ -152,6 +152,7 @@ public class CLIText extends TranslationBundle {
 	/***/ public String metaVar_diffAlg;
 	/***/ public String metaVar_directory;
 	/***/ public String metaVar_file;
+	/***/ public String metaVar_filepattern;
 	/***/ public String metaVar_gitDir;
 	/***/ public String metaVar_hostName;
 	/***/ public String metaVar_linesOfContext;