Fixes and improvements (#534)

Documentation/gps.md

@@ -4,12 +4,16 @@
 
 ### Beitian BH-222Q
 
+Currently not working.
+
 115200 baud, U-Blox 10 clone, defaults to binary messages
 
 https://www.beitian.com/en/pd.jsp?id=1677
 
 ### Beitian BN-357ZF
 
+Configure as MTK L76B in GPS settings, or auto-detect as MTK L76K.
+
 9600 baud, L76K clone
 
 https://www.beitian.com/en/sys-pd/879.html
@@ -20,7 +24,9 @@ https://www.beitian.com/en/sys-pd/879.html
 
 https://www.datasheethub.com/gy-neo6mv2-flight-control-gps-module/
 
-### M5Stack GPS
+### M5Stack Mini GPS (AT6558)
+
+Configure as ATGM336H.
 
 9600 baud, AT6558 + MAX2659 (LNA)