Stop rewriting history

Now that we’ve started landing and mentioning pull requests, every
rewrite will spam the timeline for those pull requests.

Retconning the history of reworking the pre-book docs helped preserve
the ability to see what changed in migrating to the book, but it was
time-consuming, and soon we will stub our pre-book docs to point to
the book anyway.

README.md

@@ -17,6 +17,5 @@ Or if you have [Nix](https://nixos.org/download/) (the package manager):
 $ nix-shell --run 'mdbook serve --open'
 ```
 
-**This book is still in early development!**
-In the table of contents, \* denotes chapters that have been imported from our existing docs, and still need to be copyedited or reworked.
-During this early stage of development, we’ll be frequently rewriting the Git history, so please be patient with us when making pull requests.
+**This book is a work in progress!**
+In the table of contents, \* denotes chapters that were recently added or imported from older docs, and still need to be copyedited or reworked.

src/title-page.md

@@ -8,9 +8,8 @@ Work is still ongoing to make Servo consumable as a webview library, so for now,
 
 This book will be your guide to building and running servoshell, hacking on and contributing to Servo, the architecture of Servo, and how to consume Servo and its libraries.
 
-**This book is still in early development!**
-In the table of contents, \* denotes chapters that have been imported from our existing docs, and still need to be copyedited or reworked.
-During this early stage of development, we’ll be frequently rewriting the Git history, so please be patient with us if you make a pull request.
+**This book is a work in progress!**
+In the table of contents, \* denotes chapters that were recently added or imported from older docs, and still need to be copyedited or reworked.
 
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