Add a guide entry to show how to implement the logic for "older" and "newer" posts

[csells]

ala the bottom of home page on sellsbrothers.com, i.e. "Older Entries ->":

or the bottom of any of the subsequent pages, i.e. "<- Newer Entries" and "Older Entries ->":

or the bottom of the last page of posts, i.e. "<- Newer Entries":