Pin indirect docs requirements.

Author: bwoodsend

docs/requirements.txt

@@ -1,8 +1,16 @@
-docutils==0.16
 https://github.com/bwoodsend/friendly-octo-waffle/archive/refs/heads/master.zip
 m2r2==0.2.8
-Sphinx==4.0.2
+Sphinx==4.2.0
+sphinx-autodoc-typehints==1.11.1
 sphinx-copybutton==0.3.3
 sphinxcontrib-websupport==1.1.0
 sphinx-rtd-theme==0.5.0
-sphinx-autodoc-typehints==1.11.1
+
+# Indirect dependencies.
+docutils==0.16
+mistune==0.8.4
+sphinxcontrib-applehelp==1.0.2
+sphinxcontrib-devhelp==1.0.2
+sphinxcontrib-htmlhelp==2.0.0
+sphinxcontrib-jsmath==1.0.1
+sphinxcontrib-qthelp==1.0.3