Fix line length

Author: jyn514

src/building/bootstrapping.md

@@ -131,7 +131,8 @@ This is a detailed look into the separate bootstrap stages.
 The convention `x.py` uses is that:
 - A `--stage N` flag means to run the stage N compiler (`stageN/rustc`).
 - A "stage N artifact" is an artifact that is _produced_ by the stage N compiler.
-- The "stage (N+1) compiler" is assembled from "stage N artifacts". This process is called _uplifting_.
+- The "stage (N+1) compiler" is assembled from "stage N artifacts". This
+  process is called _uplifting_.
 
 For example, `x.py build --stage 0` means to build with the beta `rustc`, and
 `test --stage 0` isn't really meaningful (it's not running tests on your changes,
@@ -148,7 +149,8 @@ will later be uplifted to stage1_.
 In each stage, two major steps are performed:
 
 1. `std` is compiled by the stage N compiler.
-2. That `std` is linked to programs built by the stage N compiler, including the stage (N+1) compiler.
+2. That `std` is linked to programs built by the stage N compiler, including
+   the stage (N+1) compiler.
 
 This is somewhat intuitive if one thinks of the stage (N+1) compiler as "just"
 another program we are building with the stage N compiler:
@@ -169,7 +171,8 @@ The stage 1 artifacts are what is shipped to end-users, including `stage2/bin/ru
 
 Note that there are two `std` libraries in play here:
 1. The library _linked_ to `stageN/rustc`, which was built by stage N-1 (stage N-1 `std`)
-2. The library _used to compile programs_ with `stageN/rustc`, which was built by stage N (stage N `std`).
+2. The library _used to compile programs_ with `stageN/rustc`, which was
+   built by stage N (stage N `std`).
 
 stage N `std` is pretty much necessary for any useful work with the compiler.
 Without it, you can only compile programs with `#![no_core]` -- not terribly useful!