That strip is included in the book, along with many others about Snoopy's experiences as he struggles to write his novel, "It was a dark and stormy night." For my money, that would have been enough, but the book also includes more than 30 short essays by successful authors, most with "tips" for struggling writers like Snoopy.
Here is an excerpt from the piece by Sue Grafton:
One of the most difficult decisions an unpublished writer makes is when to take advice and when to ignore all you well-meaning critics and do it your way. [This is in response to a strip in which Lucy has just suggested that Snoopy change his title.] (Almost) ever work of fiction can bear improvement. When you're first starting out, it's hard to know how much is enough and how much is too much, where you've engaged your reader and where you've bored her to tears. It's tempting to submit your manuscript to everyone you know: friends and relatives, co-workers, classmates, members of your critique group. It's natural to want feedback--some snese of how you're doing so you'll know what to do next.
This is good advice. But not nearly as fun as the comics.