docs: update README

README.md

@@ -7,13 +7,26 @@ A seamless launcher for Terraform.
 
 ## Installation
 
+### Homebrew
+
+**Note:** installing `terraform-demux` via Homebrew will automatically create a symlink named `terraform`.
+
+1. `brew tap etsy/terraform-demux https://github.com/etsy/terraform-demux`
+2. `brew install terraform-demux`
+
+### Manual
+
 1. Grab the latest binary from the [releases page](https://github.com/etsy/terraform-demux/releases)
 2. Copy it to a location in your `$PATH` as `terraform` (or leave it as `terraform-demux` if you'd like)
 
 ## Usage
 
 Simply navigate to any folder that contains Terraform configuration and run `terraform` as you usually would. `terraform-demux` will attempt to locate the appropriate [version constraint](https://www.terraform.io/docs/language/expressions/version-constraints.html) by searching in the current working directory and recursively through parent directories. If `terraform-demux` cannot determine a constraint, it will default to the latest possible version.
 
-## Where does `terraform-demux` keep its data?
+### Logging
+
+Setting the `DEMUX_LOG` environment variable to any non-empty value will cause `terraform-demux` to write out debug logs to `stderr`.
+
+## Cache Directory
 
-`terraform-demux` keeps a cache of Hashicorp's releases index and downloaded Terraform binaries in the directory returned by [os.UserCacheDir](https://golang.org/pkg/os/#UserCacheDir), under `terraform-demux/`.
+`terraform-demux` keeps a cache of Hashicorp's releases index and downloaded Terraform binaries in the directory returned by [os.UserCacheDir](https://golang.org/pkg/os/#UserCacheDir), under `terraform-demux/` (e.g. `~/Library/Caches/terraform-demux/` on MacOS).