Apply suggestions from code review

Co-authored-by: Joshua Nelson <[email protected]>

Author: shepmaster

src/building/new-target.md

@@ -16,15 +16,10 @@ An example would be:
 
 ```
 cd src/llvm_project
-
 git remote add my-target-llvm some-llvm-repository
-
 git checkout my-target-llvm/my-branch
-
 cd ..
-
 git add llvm_target
-
 git commit -m 'Use my custom LLVM'
 ```
 
@@ -97,7 +92,7 @@ cross-compile `rustc`:
 
 ```
 DESTDIR=/path/to/install/in \
-x.py install -i --stage 1 --host aarch64-apple-darwin.json --target aarch64-apple-darwin \
+./x.py install -i --stage 1 --host aarch64-apple-darwin.json --target aarch64-apple-darwin \
 src/librustc src/libstd
 ```