Fix unbalanced quotes in assert.notInclude example

[haykam821]

This pull request fixes two lines in the example for assert.notInclude using single quotes around the string but also including a single quote in the string:

'this doesn't work'

I have changed the erroneous examples to use double quotes around the string instead, so there is no longer a syntax error:

"this doesn't break!"

[codecov]

Codecov Report

Merging #1200 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1200   +/-   ##
=======================================
  Coverage   94.51%   94.51%           
=======================================
  Files          32       32           
  Lines        1676     1676           
  Branches      404      404           
=======================================
  Hits         1584     1584           
  Misses         92       92

Impacted Files	Coverage Δ
lib/chai/interface/assert.js	93.1% <ø> (ø)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 0064f26...c9eacb7. Read the comment docs.

[astorije]

@meeber, @keithamus, npmjs has recently invalidated all tokens, so a new one needs to be set up in the .travis.yml config file. I hit the same issue very recently at thelounge/thelounge#2716.