docs: first cut at installation instructions

Author: ctreatma

README.md

@@ -4,7 +4,11 @@
 
 ## Installation
 
-TODO
+[Equinix CLI releases](https://github.com/equinix/cli/releases/latest) contain precompiled binaries for a variety of architectures.
+
+1. Download the appropriate binary for your platform from the desired Equinix CLI release
+2. Rename the downloaded file to `equinix`
+3. Run `chmod +x equinix` to make the downloaded file executable
 
 ## Usage