Add web config info for rtcmMinElev

Author: PaulZC

Firmware/RTK_Everywhere/AP-Config/index.html

@@ -377,7 +377,7 @@
                             <div class="form-group row">
                                 <label for="rtcmMinElev" class="col-sm-4 col-6 col-form-label">Min SV Elevation for RTCM:
                                     <span class="tt" data-bs-placement="right"
-                                        title="Minimum elevation in degrees for a GNSS satellite to be used for RTCM corrections.">
+                                        title="Minimum elevation in degrees for a GNSS satellite to be used for RTCM corrections. Default: -90">
                                         <span class="icon-info-circle text-primary ms-2"></span>
                                     </span>
                                 </label>