DOC: Update links to Sphinx

Author: thewtex

Documentation/Contribute/WriteANewExample.rst

@@ -199,10 +199,10 @@ Note that the breathelink directive is a custom one which makes use of:
 .. _external hyperlink target: http://docutils.sourceforge.net/docs/user/rst/quickref.html#external-hyperlink-targets
 .. _doxygenclass directive:    https://breathe.readthedocs.io/en/latest/class.html
 .. _figure directive:          http://docutils.sourceforge.net/docs/ref/rst/directives.html#figure
-.. _literalinclude directive:  http://sphinx.pocoo.org/markup/code.html?highlight=literalinclude#directive-literalinclude
+.. _literalinclude directive:  https://sphinx-doc.org/markup/code.html?highlight=literalinclude#directive-literalinclude
 .. _literal block:             http://docutils.sourceforge.net/docs/user/rst/quickref.html#literal-blocks
 .. _Pygments:                  http://pygments.org/
-.. _Sphinx index directive:    http://sphinx.pocoo.org/markup/misc.html#directive-index
+.. _Sphinx index directive:    https://sphinx-doc.org/markup/misc.html#directive-index
 .. _reStructuredText:          http://docutils.sourceforge.net/rst.html
 .. _doxylink:                  https://pythonhosted.org/sphinxcontrib-doxylink/
 .. _VTK:                       https://vtk.org

Documentation/Contribute/index.rst

@@ -29,6 +29,6 @@ facets are important to the success of the project.
 .. _ITK Examples repository: https://github.com/InsightSoftwareConsortium/ITKExamples
 .. _Git:                     https://git-scm.com/
 .. _reStructuredText:        http://docutils.sourceforge.net/rst.html
-.. _Sphinx:                  http://sphinx.pocoo.org/
+.. _Sphinx:                  https://sphinx-doc.org/
 .. _Quick reStructuredText:  http://docutils.sourceforge.net/docs/user/rst/quickref.html
 .. _Dashboard:               https://open.cdash.org/index.php?project=Insight&filtercount=1&showfilters=1&field1=groupname/string&compare1=63&value1=Examples

Formatting/templates/layout.html

@@ -33,7 +33,7 @@
       <br />
       Last updated on {{ last_updated|e }}.
       <br />
-      Created using <a href="http://sphinx.pocoo.org/">Sphinx</a> {{
+      Created using <a href="https://sphinx-doc.org/">Sphinx</a> {{
       sphinx_version|e }},
       and <a href="https://cmake.org/">CMake</a>.
     </div>

README.rst

@@ -84,7 +84,7 @@ Run the bash script ``SetupForDevelopment.sh``::
 .. _CMake: https://cmake.org/
 .. _Git: https://git-scm.com/
 .. _ITK: https://itk.org/
-.. _Sphinx: http://sphinx.pocoo.org/
+.. _Sphinx: https://sphinx-doc.org/
 .. _Github Issues: https://github.com/InsightSoftwareConsortium/ITKExamples/issues
 .. _Python: https://python.org/
 .. _gnuplot: https://www.gnuplot.info/