python docs: link to GRASS GIS project site fixed

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@71893 15284696-431f-4ddb-bdfa-cd5b030d7da7

lib/python/docs/src/index.rst

@@ -4,8 +4,7 @@ GRASS GIS Python library documentation
 Python, a widely used general-purpose, high-level programming language 
 provides a powerful scripting interface. Being easy-to-use yet 
 powerful, it enables users to efficiently exploit the capabilities
-of the [GRASS GIS](https://grass.osgeo.org/) software.
-Python scripts for GRASS GIS can be written at 
+of the `GRASS GIS` software. Python scripts for GRASS GIS can be written at 
 high level (GRASS GIS modules) as well as at low level (GRASS GIS 
 libraries) through a dedicated interface. The graphical user interface 
 and the GRASS GIS Temporal Framework are entirely written in Python.
@@ -38,3 +37,4 @@ Contents:
    gunittest_testing
    pydispatch
 
+.. _GRASS GIS: https://grass.osgeo.org/