webui: add common telegram bot help.

package/thingino-webui/files/var/www/x/_tg_bot.cgi

@@ -0,0 +1,24 @@
+<div class="modal fade" id="helpModal" tabindex="-1">
+<div class="modal-dialog">
+<div class="modal-content">
+<div class="modal-header">
+<h5 class="modal-title">To create a Telegram bot</h5>
+<button type="button" class="btn-close" data-bs-dismiss="modal" aria-label="Close"></button>
+</div>
+<div class="modal-body">
+<p>To create a channel for your Telegram bot:</p>
+<ol>
+<li>Start a chat with <a href="https://t.me/BotFather">@BotFather</a></li>
+<li>Enter <code>/start</code> to start a session.</li>
+<li>Enter <code>/newbot</code> to create a new bot.</li>
+<li>Give your bot channel a name, e.g. <i>cool_cam_bot</i>.</li>
+<li>Give your bot a username, e.g. <i>CoolCamBot</i>.</li>
+<li>Copy the token assigned to your new bot by the BotFather, and paste it to the form.</li>
+</ol>
+</div>
+<div class="modal-footer">
+<button type="button" class="btn btn-secondary" data-bs-dismiss="modal">Close</button>
+</div>
+</div>
+</div>
+</div>