Reduce Sphinx plugin warnings during documentation builds

Adjusts `doc/conf.py.in` to suppress warning from several Sphinx plugins, these
warnings are false-positives and are not helpful for improving the quality of
the documentation, errors will still be shown if they are emitted.

Signed-off-by: Winford <winford@object.stream>

Author: UncleGrumpy

doc/conf.py.in

@@ -63,7 +63,9 @@ extensions = [
 suppress_warnings = [
     'epub.unknown_project_files',
     'misc.highlighting_failure',
-    'toc.excluded'
+    'toc.excluded',
+    'myst.*',
+    'breathe.*'
 ]
 
 # Add any paths that contain templates here, relative to this directory.