Document requirements for getHelp in CommandInfo

Change-Id: I12040fff5c0cfdb164d0429c7378df15de074f8d
Reviewed-on: http://gerrit.dmdirc.com/1015
Automatic-Compile: DMDirc Local Commits <dmdirc@googlemail.com>
Automatic-Compile: Shane Mc Cormack <shane@dmdirc.com>
Reviewed-by: Shane Mc Cormack <shane@dmdirc.com>

src/com/dmdirc/commandparser/CommandInfo.java

@@ -45,6 +45,19 @@ public interface CommandInfo {
     
     /**
      * Returns a string representing the help message for this command.
+     * <p>
+     * The help text should generally be one line, and must start with
+     * the name of the command. It should then summarise the arguments of
+     * that command, using <code>&lt;angled&gt;</code> brackets for required
+     * arguments, and <code>[square]</code> brackets for optional arguments.
+     * Where multiple possibilities exist, they are typically separated by a
+     * pipe (<code>|</code>), for example: <code>command [--arg1|--arg2]</code>.
+     * The usage summary should then be followed by a dash and a brief
+     * summary of the purpose of the command.
+     * <p>
+     * A typical help message would look similar to:
+     * <p>
+     * <code>command [--arg &lt;param_for_arg&gt;] [someparam] - does x, y and z</code>
      *
      * @return the help message for this command
      */