Broken formatting on PCA docs
The docs generated for #431 at https://mratsim.github.io/Arraymancer/pca.html have broken formatting:

- Upstream bug on the type: 
![image](https://user-images.githubusercontent.com/22738317/79689446-2dc5f300-8255-11ea-90df-ed4d1d5c9430.png)
- Random bolding: 
![image](https://user-images.githubusercontent.com/22738317/79689458-3d453c00-8255-11ea-9591-b4d3103aeadd.png) and 
![image](https://user-images.githubusercontent.com/22738317/79689466-51893900-8255-11ea-9baf-28cbc0e4004f.png)
- 
![image](https://user-images.githubusercontent.com/22738317/79689474-61088200-8255-11ea-9c5f-239414532317.png)

One `requires`, `inputs`, `returns` are probably worth to be bold.


