Resolve app.add_stylesheet() is deprecated

/w/workspace/docs-tox-verify-silicon/docs/conf.py:74:
	RemovedInSphinx40Warning: The app.add_stylesheet() is deprecated.
	Please use app.add_css_file() instead.

Signed-off-by: Thanh Ha <zxiiro@gmail.com>
Change-Id: I2d44a41d240381e2b1f9dee70aa5af2bed7acd1d

diff --git a/docs/conf.py b/docs/conf.py
index bf94794559ed0b19256fd87ae30123bc9658f81d..e808709009b1f2d241e09f42e06264adb9811188 100755 (executable)
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -70,4 +70,4 @@ html_context = {
 }
 
 def setup(app):
-    app.add_stylesheet("css/ribbon.css")
+    app.add_css_file("css/ribbon.css")