manual libinit: add config option python_path (#2256)

lib/init/grass.html

@@ -49,7 +49,7 @@
 (<em><a href="wxGUI.html">wxGUI</a></em>) should be used
 
 <dt><b>--config</b>
-<dd> Prints GRASS configuration parameters (options: arch, build, compiler, date, path, revision, svn_revision, version)
+<dd> Prints GRASS configuration parameters (options: arch, build, compiler, date, path, python_path, revision, svn_revision, version)
 
 <dt><b>--exec EXECUTABLE</b>
 <dd> Execute GRASS module or script. The provided executable will be executed in a GRASS GIS non-interactive session.
@@ -132,6 +132,7 @@ version parameters, with the options:
 <li><b>compiler</b>: (e.g., <tt>gcc</tt>)</li>
 <li><b>date</b>: (e.g., <tt>Tue Mar 31 20:34:57 2020 +0200</tt>)</li>
 <li><b>path</b>: (e.g., <tt>/usr/lib64/grass</tt>)</li>
+<li><b>python_path</b>: (e.g., <tt>/usr/lib64/grass/etc/python</tt>)</li>
 <li><b>revision</b>: (e.g., <tt>745ee7ec9</tt>)</li>
 <li><b>svn_revision</b>: (e.g., <tt>062bffc8</tt>)</li>
 <li><b>version</b>: (e.g., <tt>8.0.0dev</tt>)</li>