update depot_tools_tutorial to include git reset issue

Bug:997395
Change-Id: Iabd189cb05ee9c87866697cc24c7d08d200b9b91
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2412474
Reviewed-by: Josip Sokcevic <sokcevic@google.com>
Commit-Queue: Gavin Mak <gavinmak@google.com>

man/html/depot_tools_tutorial.html

@@ -1105,8 +1105,22 @@ you started on.</p></div>
 <td class="icon">
 <div class="title">Note</div>
 </td>
-<td class="content">Running <code>git rebase-update</code> will update all your branches, but it will not
-automatically run <code>gclient sync</code> to update your dependencies.</td>
+<td class="content">
+<div class="ulist"><ul>
+<li>
+<p>
+Running <code>git rebase-update</code> will update all your branches, but it will not
+automatically run <code>gclient sync</code> to update your dependencies.
+</p>
+</li>
+<li>
+<p>
+Use caution when running <code>git reset</code> as it may result in unexpected behavior of 
+<code>git rebase-update</code> and <code>depot_tools</code> in general - see 
+<a href="https://bugs.chromium.org/p/chromium/issues/detail?id=997395">crbug.com/997395</a>.
+</p>
+</li>
+</ul></div>
 </tr></table>
 </div>
 </div>

man/man7/depot_tools_tutorial.7

@@ -420,7 +420,7 @@ Once you\(cqre done resolving all of the merge conflict, just run git rebase\-up
 .ps -1
 .br
 .sp
-Running git rebase\-update will update all your branches, but it will not automatically run gclient sync to update your dependencies\&.
+Running git rebase\-update will update all your branches, but it will not automatically run gclient sync to update your dependencies\&. Use caution when running git reset as it may result in unexpected behavior of git rebase\-update and \fIdepot_tools\fR in general.
 .sp .5v
 .RE
 .SH "MANAGING MULTIPLE CLS"