README: point to cuelang.org for install docs

This updates the README to point to cuelang.org for the full list of
installation methods made available by the project (and others).

This change means we don't have to keep two lists of methods in sync
across this repo and the main site. Instead, we link only to the two
primary methods exposed directly by the project (executable downloads
and build-from-source), whilst mentioning that the Docker-compatible
container image is documented on the main site.

Also: point the GitHub release link to the latest build, and change the
prose holding the link to make it clearer that clicking the link won't
immediately begin a download onto the user's machine.

Closes cue-lang/docs-and-content#63

Signed-off-by: Jonathan Matthews <[email protected]>
Change-Id: Ibe0b0b625072facb40607606b1ab5643dc221010
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1197388
TryBot-Result: CUEcueckoo <[email protected]>
Reviewed-by: Paul Jolly <[email protected]>

Author: jpluscplusm

README.md

@@ -91,17 +91,14 @@ Some aspects of this are:
 
 ### Download and Install
 
-#### Release builds
-
-[Download](https://github.com/cue-lang/cue/releases) the latest release from GitHub.
-
-#### Run with Docker
+The full range of installation methods for the `cue` command are listed on the
+[cuelang.org site](https://cuelang.org/docs/introduction/installation/),
+including the official container image suitable for use with Docker.
+Here are two common ways to install the command:
 
-	docker run cuelang/cue version
-
-#### Install using Homebrew
+#### Release builds
 
-	brew install cue-lang/tap/cue
+Download the [latest release](https://github.com/cue-lang/cue/releases/latest/) from GitHub.
 
 #### Install from Source