Fixed syntax error in README.rst

Author: agronholm

README.rst

@@ -41,10 +41,13 @@ considered as tested only under a few environments) specify the ``citext`` extra
     pip install sqlacodegen[citext]
 
 
-To include support for the PostgreSQL ``GEOMETRY``, ``GEOGRAPHY``, and ``RASTER`` types (which should be
-considered as tested only under a few environments) specify the ``geoalchemy2`` extra::
-    pip install sqlacodegen[geoalchemy2]
+To include support for the PostgreSQL ``GEOMETRY``, ``GEOGRAPHY``, and ``RASTER`` types
+(which should be considered as tested only under a few environments) specify the
+``geoalchemy2`` extra:
+
+.. code-block:: bash
 
+    pip install sqlacodegen[geoalchemy2]
 
 
 Quickstart