update link to icons repo (merge https://trac.osgeo.org/grass/changeset/68316 from trunk)

git-svn-id: https://svn.osgeo.org/grass/grass/branches/releasebranch_7_0@68317 15284696-431f-4ddb-bdfa-cd5b030d7da7

gui/wxpython/docs/wxGUI.html

@@ -718,7 +718,7 @@ Stepan Turek, OSGeoREL, Czech Technical University in Prague, Czech Republic<br>
 Tereza Fiedlerova, OSGeoREL, Czech Technical University in Prague, Czech Republic<br>
 Matej Krejci, OSGeoREL, Czech Technical University in Prague, Czech Republic<br><br>
 
-Icons created by <a href="http://robert.szczepanek.pl">Robert Szczepanek</a>, Poland (<a href="https://svn.osgeo.org/osgeo/graphics/trunk/toolbar-icons/24x24/">SVN</a>)
+Icons created by <a href="http://robert.szczepanek.pl">Robert Szczepanek</a>, Poland (<a href="https://github.com/Cracert/GIS-icons">Git repository</a>)
 
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