Handbooks: Chapters list items drop to new line on tablet

[pbujok]

When you scale down the page on handbooks (for example the Rest API Handbook, ​https://developer.wordpress.org/rest-api/), the chapter list items drop down to a new line. Instead they should wrap the text if it is too long.

Issue screenshot: ​https://puu.sh/sE1Np/ddb9bd49ae.png

Here is the code that should be added:

.devhub-wrap #sidebar ul li > a {
    max-width: 75%;
}

or replace width: 225px with width: 75%.

Fixed screenshot: ​https://puu.sh/sE22S/ccf1d120cf.png

[coffee2code]

In 4494:

developer.wordpress.org: Fix wrapping of Chapters list items at smaller page widths.

Props pbujok.
Fixes #2299.