Additional tweaks to README.pg_sphere

Author: esabol

README.pg_sphere

@@ -49,10 +49,9 @@ UPDATING AN EXISTING INSTALLATION:
   psql -c "select pg_sphere_version();" <database>
   psql -c "SELECT * FROM pg_available_extension_versions WHERE name = 'pg_sphere';"
 
-REGRESSION TESTS (as the same user as the currently running PostgreSQL server):
+REGRESSION TEST (as the same user as the currently running PostgreSQL server):
 
   make installcheck
-  make test
 
 LONG REGRESSION TEST:
 
@@ -63,4 +62,6 @@ The 'make' program must be compatible with GNU make.
 For more information or to report issues or to help with development, please
 refer to https://github.com/postgrespro/pgsphere/
 
+Original repository for pgSphere: https://github.com/akorotkov/pgsphere
+
 Have a lot of fun!