README updates

README.md

@@ -3,14 +3,13 @@
 This action sets up a PostgreSQL server with PostGIS extension.  The code is based on the [ikalnytskyi/action-setup-postgres](https://github.com/ikalnytskyi/action-setup-postgres) action.
 
 * Runs on Linux, macOS and Windows runners.
-* Adds PostgreSQL [binaries][1] (e.g. `psql`) to `PATH`.
-* Uses PostgreSQL installed in [GitHub Actions Virtual Environments][2].
+* Adds PostgreSQL [binaries](https://www.postgresql.org/docs/current/reference-client.html) (e.g. `psql`) to `PATH`.
+* Uses PostgreSQL installed in [GitHub Actions Virtual Environments](https://github.com/actions/virtual-environments).
 * Installs the correct version of PostGIS and runs `CREATE EXTENSION postgis` in the new database.
-* [Easy to check][3] that IT DOES NOT contain malicious code.
-
-[1]: https://www.postgresql.org/docs/current/reference-client.html
-[2]: https://github.com/actions/virtual-environments
-[3]: action.yml
+  * Linux version is installed from the [PostGIS apt repository](https://postgis.net/install/).
+  * Windows version is installed from the [OSGeo](https://download.osgeo.org/postgis/windows/).
+  * MacOS version is installed using [Homebrew package](https://formulae.brew.sh/formula/postgis).
+* [Easy to check][action.yml] that IT DOES NOT contain malicious code.
 
 ## Usage