docs(map_projection_loader): add limitations

Signed-off-by: Yamato Ando <[email protected]>

map/map_projection_loader/README.md

@@ -28,6 +28,14 @@ sample-map-rosbag
 projector_type: local
 ```
 
+#### Limitation
+
+The functionality that requires latitude and longitude will become unavailable.
+
+The currently identified unavailable functionalities are:
+- GNSS localization
+- Sending the self-position in latitude and longitude using ADAPI
+
 ### Using MGRS
 
 If you want to use MGRS, please specify the MGRS grid as well.
@@ -39,6 +47,10 @@ vertical_datum: WGS84
 mgrs_grid: 54SUE
 ```
 
+#### Limitation
+
+It cannot be used with maps that span across two or more MGRS grids. Please use it only when it falls within the scope of a single MGRS grid.
+
 ### Using LocalCartesianUTM
 
 If you want to use local cartesian UTM, please specify the map origin as well.