Fix overlap in DocService sidebar (#2470)
Fix overlap in DocService sidebar (#2470)

This PR fixes an issue with overlapping method type and name in the DocService sidebar.

### Before
![before](https://user-images.githubusercontent.com/1769968/74077791-4ef4b100-4a66-11ea-9452-81a9f4b25d95.png)

### After
![after](https://user-images.githubusercontent.com/1769968/74077793-52883800-4a66-11ea-830c-4ff1e1fc6f60.png)

#### Notes
- The `spacing` parameter is a multiple of 8 pixels. I can adjust if necessary.
kojilin/armeria,trustin/armeria,minwoox/armeria,trustin/armeria,line/armeria,kojilin/armeria,line/armeria,anuraaga/armeria,anuraaga/armeria,anuraaga/armeria,kojilin/armeria,minwoox/armeria,line/armeria,line/armeria,anuraaga/armeria,trustin/armeria,minwoox/armeria,minwoox/armeria,minwoox/armeria,anuraaga/armeria,line/armeria,anuraaga/armeria,trustin/armeria,minwoox/armeria,trustin/armeria,kojilin/armeria,kojilin/armeria,trustin/armeria,kojilin/armeria,line/armeria