docs: Upgrade documentation tools

Signed-off-by: Anton Komlev <anton.komlev@arm.com>
Change-Id: Iaa12abed9f34017025e17c1bfc7df8f45c12ac13
diff --git a/docs/conf.py.in b/docs/conf.py.in
index eeff3ba..7efc1db 100644
--- a/docs/conf.py.in
+++ b/docs/conf.py.in
@@ -47,7 +47,7 @@
 # ones.
 extensions = [
     'sphinx.ext.imgmath',
-    'm2r', #Support markdown files. Needed for external code.
+    'm2r2', #Support markdown files. Needed for external code.
     'sphinx.ext.autosectionlabel', #Make sphinx generate a label for each section
     'sphinxcontrib.plantuml', #Add support for PlantUML drawings
     'sphinxcontrib.rsvgconverter', #Add support for SVG to PDF
@@ -127,7 +127,7 @@
 
 #Add custom css for HTML. Used to allow full page width rendering
 def setup(app):
-    app.add_stylesheet('css/tfm_custom.css')
+    app.add_css_file('css/tfm_custom.css')
 
 # -- Options for HTMLHelp output ---------------------------------------------