Adds README changes for installation of experimental features (#124)

README.md

@@ -13,6 +13,7 @@ for working with [the Ion data format](https://amzn.github.io/ion-docs/docs/spec
 * [Installation](#installation)
     * [via `brew`](#via-brew)
     * [via `cargo`](#via-cargo)
+    * [Installing experimental subcommand for code generation](#installing-experimental-subcommand-for-code-generation)
 * [Build Instructions](#build-instructions)
     * [From source](#from-source)
     * [Using Docker](#using-docker)
@@ -171,6 +172,22 @@ To install `ion-cli`, run the following command:
 cargo install ion-cli
 ```
 
+### Installing experimental subcommand for code generation
+
+If you are looking into accessing all features with `brew` (including `experimental` features, currently only
+includes `generate`
+subcommand under `beta`) of `ion-cli`, run:
+
+```bash
+brew install ion-cli --HEAD
+```
+
+If you are looking into accessing all features with `cargo` (including `experimental` features) of `ion-cli`, run:
+
+```shell
+cargo install ion-cli --all-features
+```
+
 Then make sure that `~/.cargo/bin` is on your `$PATH`. You can confirm that it
 has been installed successfully by running:
 

code-gen-projects/README.md

@@ -78,6 +78,7 @@ tasks {
     }
 }
 ```
+_Note: Code generation subcommand `generate` is under a feature flag. It is available through `brew install ion-cli --HEAD` or `cargo install ion-cli --all-features`._
 
 ## /rust
 
@@ -131,4 +132,5 @@ fn main() {
     println!("cargo:rerun-if-changed=input/");
     println!("cargo:rerun-if-changed=schema/");
 }
-```
+```
+_Note: Code generation subcommand `generate` is under a feature flag. It is available through `brew install ion-cli --HEAD` or `cargo install ion-cli --all-features`._