highlight Dockerfile.dev as Dockerfile in github ui (home-assistant#36933)

adaamz · web-flow · commit 0054904454af · 2020-06-22T14:45:57.000+02:00
diff --git a/.gitattributes b/.gitattributes
@@ -8,3 +8,5 @@
 *.png binary
 *.zip binary
 *.mp3 binary
+
+Dockerfile.dev linguist-language=Dockerfile
