[editorconfig] add yml and meson_options rules

.editorconfig

@@ -10,3 +10,11 @@ insert_final_newline = true
 [*.{c,h,cpp,hpp}]
 indent_style = tab
 indent_size = 2
+
+[*.yml]
+indent_style = space
+indent_size = 2
+
+[meson_options.txt]
+indent_style = space
+indent_size = 2