Flags added to convert doc build warnings to errors

- To ensure that the CI will fail if there are broken links or images.
- Fixes #9778

.readthedocs.yml

@@ -9,3 +9,5 @@ python:
       path: .
       extra_requirements:
         - docs
+sphinx:
+  fail_on_warning: True

docs/Makefile

@@ -2,7 +2,7 @@
 #
 
 # You can set these variables from the command line.
-SPHINXOPTS    =
+SPHINXOPTS    = -W --keep-going -n
 SPHINXBUILD   = sphinx-build
 PAPER         =
 BUILDDIR      = _build