This specifies the number of page links to include in the summary of
the results.
For example, if we are on page 22 of 5,000 total results, by default
direct links will be shown to pages 18 through 27 (for a total of 10
links). If Page Links Shown is set to 20, it will show
links 13 through 32, for a total of 20 page links.