fix(README): update "sections below" reference (#1210)

This PR updates the "sections below" reference to point to the installation docs, since the details and alternatives are not present in the sections below of the README.

README.md

@@ -20,7 +20,7 @@ https://bazelbuild.github.io/rules_nodejs/
 ## Quickstart
 
 This is the fastest way to get started.
-See sections below for details and alternative methods.
+See the [installation documentation](https://bazelbuild.github.io/rules_nodejs/install.html) for details and alternative methods.
 
 ```sh
 $ npm init @bazel