doc: Upgrade docutils.sourceforge.io links to HTTPS

Also change any docutils.sourceforge.net link to io
top level domain.

3 files changed, 3 insertions, 3 deletions

diff --git a/doc/extdev/index.rst b/doc/extdev/index.rst
index d9c04f413..d210ee49b 100644
--- a/doc/extdev/index.rst
+++ b/doc/extdev/index.rst
@@ -112,7 +112,7 @@ in which a Sphinx project is built: this works in several phases.
    existing files are read, temporary nodes are created.
 
    There are nodes provided by docutils, which are documented `in the docutils
-   documentation <http://docutils.sourceforge.net/docs/ref/doctree.html>`__.
+   documentation <https://docutils.sourceforge.io/docs/ref/doctree.html>`__.
    Additional nodes are provided by Sphinx and :ref:`documented here <nodes>`.
 
    During reading, the build environment is updated with all meta- and cross
diff --git a/doc/extdev/markupapi.rst b/doc/extdev/markupapi.rst
index 7a21f8126..8fc884d7c 100644
--- a/doc/extdev/markupapi.rst
+++ b/doc/extdev/markupapi.rst
@@ -149,4 +149,4 @@ return ``node.children`` from the Directive.
 
    `Creating directives`_ HOWTO of the Docutils documentation
 
-.. _Creating directives: http://docutils.sourceforge.net/docs/howto/rst-directives.html
+.. _Creating directives: https://docutils.sourceforge.io/docs/howto/rst-directives.html
diff --git a/doc/extdev/parserapi.rst b/doc/extdev/parserapi.rst
index 0beb51711..1bd03fd09 100644
--- a/doc/extdev/parserapi.rst
+++ b/doc/extdev/parserapi.rst
@@ -8,7 +8,7 @@ Parser API
     The Parser analyzes the input document and creates a node tree
     representation.
 
-__ http://docutils.sourceforge.net/docs/dev/hacking.html#parsing-the-document
+__ https://docutils.sourceforge.io/docs/dev/hacking.html#parsing-the-document
 
 In Sphinx, the parser modules works as same as docutils.  The parsers are
 registered to Sphinx by extensions using Application APIs;