boards/esp32_wrover_kit: documentation improvement
boards/esp32_wrover_kit: documentation improvement

Adds a reference to a vendor document about hardware configuration.
toonst/RIOT,mfrey/RIOT,OlegHahm/RIOT,basilfx/RIOT,mtausig/RIOT,authmillenon/RIOT,cladmi/RIOT,smlng/RIOT,ant9000/RIOT,jasonatran/RIOT,authmillenon/RIOT,kYc0o/RIOT,kaspar030/RIOT,yogo1212/RIOT,x3ro/RIOT,smlng/RIOT,rfuentess/RIOT,rfuentess/RIOT,RIOT-OS/RIOT,RIOT-OS/RIOT,OTAkeys/RIOT,josephnoir/RIOT,x3ro/RIOT,yogo1212/RIOT,cladmi/RIOT,miri64/RIOT,yogo1212/RIOT,basilfx/RIOT,miri64/RIOT,cladmi/RIOT,toonst/RIOT,cladmi/RIOT,toonst/RIOT,mtausig/RIOT,jasonatran/RIOT,kaspar030/RIOT,smlng/RIOT,mfrey/RIOT,josephnoir/RIOT,OlegHahm/RIOT,cladmi/RIOT,OlegHahm/RIOT,RIOT-OS/RIOT,RIOT-OS/RIOT,rfuentess/RIOT,josephnoir/RIOT,aeneby/RIOT,kaspar030/RIOT,smlng/RIOT,ant9000/RIOT,x3ro/RIOT,toonst/RIOT,aeneby/RIOT,basilfx/RIOT,miri64/RIOT,aeneby/RIOT,basilfx/RIOT,mfrey/RIOT,mfrey/RIOT,miri64/RIOT,kYc0o/RIOT,smlng/RIOT,toonst/RIOT,OlegHahm/RIOT,OTAkeys/RIOT,authmillenon/RIOT,jasonatran/RIOT,kYc0o/RIOT,mfrey/RIOT,OTAkeys/RIOT,authmillenon/RIOT,RIOT-OS/RIOT,josephnoir/RIOT,authmillenon/RIOT,x3ro/RIOT,aeneby/RIOT,OlegHahm/RIOT,ant9000/RIOT,kYc0o/RIOT,jasonatran/RIOT,josephnoir/RIOT,yogo1212/RIOT,mtausig/RIOT,OTAkeys/RIOT,kaspar030/RIOT,ant9000/RIOT,miri64/RIOT,aeneby/RIOT,OTAkeys/RIOT,mtausig/RIOT,x3ro/RIOT,yogo1212/RIOT,rfuentess/RIOT,kaspar030/RIOT,yogo1212/RIOT,authmillenon/RIOT,kYc0o/RIOT,ant9000/RIOT,basilfx/RIOT,jasonatran/RIOT,mtausig/RIOT,rfuentess/RIOT