Add optional page-break

[intptr-t]

Since version 0.4.8, when I have to include a long word that does not fit on a single line (specifically, a hyperlink, etc.), the h1 header of the next page is out of position in the forced page break.
(#1485)

I was working on manually adding page breaks (<div style="page-break-before:always"></div>) to some sentences.
In pdfs printed from print.html with the current version, I'm suffering from a case where the h1 header comes at the end.

Is it possible to manually opt-out the page break option?

========

For example, I printed the following book using Google Chrome

.
├── book
├── book.toml
└── src
    ├── SUMMARY.md
    ├── chapter_1.md
    └── chapter_2.md

book.toml

[book]
authors = ["UserName"]
language = "en"
multilingual = false
src = "src"

chapter_1.md

# Chapter 1

<https://www.google.com/search?q=mdbook&rlz=1C5CHFA_enJP895JP903&oq=mdbook&aqs=chrome..69i57j69i59j69i60l3.795j0j1&sourceid=chrome&ie=UTF-8>

chapter_2.md

# Chapter 2
Content2

SUMMARY.md

# Summary

- [Chapter 1](./chapter_1.md)
- [Chapter 2](./chapter_2.md)

Preview

Environment

% mdbook --version
mdbook v0.4.8

% sw_vers  
ProductName:    Mac OS X
ProductVersion: 10.15.7
BuildVersion:   19H1217

% /Applications/Google\ Chrome.app/Contents/MacOS/Google\ Chrome --version
Google Chrome 91.0.4472.77 

[ehuss]

Thanks for the report! Sorry that was causing you trouble. I think this is a duplicate of #1190, so I'm going to close in favor of that. If I misunderstood, feel free to reopen. There are instructions there on how to add the option.