Add syntax highlighting

docs/charts.md

@@ -240,7 +240,7 @@ a chart in dependencies using alias as name of new dependency.
 One can use `alias` in cases where they need to access a chart
 with other name(s).
 
-````
+```yaml
 # parentchart/requirements.yaml
 dependencies:
   - name: subchart
@@ -254,7 +254,7 @@ dependencies:
   - name: subchart
     repository: http://localhost:10191
     version: 0.1.0
-````
+```
 
 In the above example we will get 3 depenendencies in all for `parentchart`
 ```