Remove a dead link from new-target.md

The "Skipping LLVM Build" section was removed in 4e48f42 (the `sysllvm` reference link was removed in 07b5693). The relevant bits were added back in ca851c6 so we no longer need to link to anything anyways.

src/building/new-target.md

@@ -20,15 +20,15 @@ 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 add llvm-project
 git commit -m 'Use my custom LLVM'
 ```
 
 ### Using pre-built LLVM
 
 If you have a local LLVM checkout that is already built, you may be
-able to configure Rust to treat your build as the [system LLVM][sysllvm]
-to avoid redundant builds.
+able to configure Rust to treat your build as the system LLVM to avoid
+redundant builds.
 
 You can tell Rust to use a pre-built version of LLVM using the `target` section
 of `config.toml`: