Portenta X8: OOTB: Add note on time to boot the board

The mentioned page won't be available at the time we boot the board,
so mention that it can take up to 15 seconds to show up after boot.

Signed-off-by: Vanessa Maegima <vanessa.maegima@foundries.io>

Author: vanmaegima

content/hardware/04.pro/boards/portenta-x8/tutorials/out-of-the-box/content.md

@@ -30,7 +30,7 @@ software:
 
 ## Connecting to the Board
 
-Once the Portenta X8 is plugged in via USB, you can open your browser and go to http://192.168.7.1 if you use Windows and Linux or http://192.168.8.1 on MacOS. This web page is hosted on the Portenta X8, from this dashboard you will be able to:
+Once the Portenta X8 is plugged in via USB, you can open your browser and go to http://192.168.7.1 if you use Windows and Linux or http://192.168.8.1 on MacOS. It can take up to 15 seconds for the board to boot up and make the page available. This web page is hosted on the Portenta X8, from this dashboard you will be able to:
 
 ![Board set up page](assets/x8-oob-main.png)
 
@@ -184,4 +184,4 @@ Make sure the name is not already being used in your Factory.
 
 Run: `journalctl -f` to see what's going on on the device
 
-![Real time tasks on CLI](assets/command-journalctl.png)
+![Real time tasks on CLI](assets/command-journalctl.png)