Cap number of files that are listed in "heads up" comment

[jdm]

We should list the first five files, followed by "and N more".

[highfive]

Hi! If you have any questions regarding this issue, feel free to make a comment here, or ask it in the #servo channel in IRC.

If you intend to work on this issue, then add @highfive: assign me to your comment, and I'll assign this to you. :smile:

[jdm]

Code: https://github.com/servo/highfive/blob/master/handlers/watchers/__init__.py

[pyfisch]

@highfive: assign me

[pyfisch]

Huhu?

@highfive: assign me

[jdm]

This repository doesn't have the "C-assigned" label present.