document rust-timer commands on the help page

Author: lqd

site/static/help.html

@@ -54,8 +54,20 @@ <h3><b><code>@rust-timer</code> commands</b></h3>
                 <code>&lt;RUNS&gt;</code> times.
             </li>
         </ul>
-        <p><code>@rust-timer</code> has more commands than just <code>@rust-timer queue</code>, but the
-            <code>queue</code> command is the most used.
+        <p><code>@rust-timer</code> has
+            <a href="https://github.com/rust-lang/rustc-perf/blob/dcae222b6a7fbb4c9e21d95bc93313ebe5107c7c/site/src/request_handlers/github.rs#L12-L21">more commands</a>
+            than just <code>@rust-timer queue</code>, but the <code>queue</code> command is the most used.
+        </p>
+        <p><code>@rust-timer build $commit</code> will queue a perf run for the given commit <code>$commit</code>.
+            It is usually invoked with the commit from a successful "try" run. (The
+            <code>queue</code> command can be seen as a shortcut that automatically selects the
+            "try" run's commit for the <code>build</code> command)
+            This command also supports the same <code>include</code>, <code>exclude</code>, and <code>runs</code> options
+            as <code>@rust-timer queue</code>.
+        </p>
+        <p>
+            The other two commands are a work in progress and will be documented here when they're
+            finalized. They are dedicated to helping diagnose the cause of regressions in rollup PRs.
         </p>
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