Fix GIS docs

GIS.md

@@ -3,15 +3,15 @@ GIS support in SQLite Foreign Data Wrapper for PostgreSQL
 
 <img src="https://www.tmapy.cz/wp-content/uploads/2021/02/postgis-logo.png" align="center" height="80" alt="PostGIS"/>	+ <img src="https://www.gaia-gis.it/fossil/libspatialite/logo" align="center" height="80" alt="SpatiaLite"/>
 
-SQLite FDW for PostgreSQL can connect PostgreSQL with [PostGIS](https://www.postgis.net/)
+SQLite FDW for PostgreSQL can connect PostgreSQL with or without [PostGIS](https://www.postgis.net/)
 to [SpatiaLite](https://www.gaia-gis.it/fossil/libspatialite/index) SQLite database file.
-This is description contains only information about GIS support without common SQL and
+This description contains only information about GIS support without common SQL and
 system descriptions from [common FDW description](README.md).
 
 Common conditions of GIS support
 --------------------------------
 
-1. SQLite FDW should be compiled with defined GIS_SUPPORT macros. See [sqlite_fdw.h](sqlite_fdw.h)
+1. SQLite FDW should be compiled with defined `GIS_SUPPORT` macros. See [sqlite_fdw.h](sqlite_fdw.h)
 2. You must install SpatiaLite header files before compilation.
 Linux packages like `libspatialite-dev` or `libspatialite-devel` can contain this files.
 3. A column should have data type (domain) name from following list:
@@ -47,6 +47,8 @@ convertable to PostGIS storage format.
 PostgGIS and SpatiaLite vector data formats
 -------------------------------------------
 
+Vector GIS data in PostGIS can be stored in a columns with `geography` or `geometry`
+data type. This columns contains a binary data.
 [Well-known binary (WKB)](https://en.wikipedia.org/wiki/Well-known_text_representation_of_geometry#Well-known_binary)
 data storage format is a standard of [Open Geospatial Consortium (OGC)](https://en.wikipedia.org/wiki/Open_Geospatial_Consortium)
 and supported by [GEOS library](https://libgeos.org). PostGIS internal GIS data