Use "$PWD" instead of `pwd` in install instructions

There's no need to promote the use of the `pwd` command when shells
export the current directory as `$PWD`. Using `$PWD` makes the
commandline work in fish as well. Additionally, quote the variable so it
works properly even if the cwd has a space in it.

diff --git a/README.md b/README.md
index d014cd6a52aba37a00a41ab0edb717094dd1eeee..c9f9e839ddf1d5dfd4bb85478e8f2454d718c513 100644 (file)
--- a/README.md
+++ b/README.md
@@ -45,7 +45,7 @@ git clone https://github.com/rust-lang/cargo
 cd cargo
 git submodule update --init
 ./.travis.install.deps.sh
-./configure --local-rust-root=`pwd`/rustc
+./configure --local-rust-root="$PWD"/rustc
 make
 make install
 ```