Removes unnecessary section from README (#176)

Author: popematt

README.md

@@ -165,6 +165,11 @@ brew tap amazon-ion/ion-cli
 brew install ion-cli
 ```
 
+To install the (potentially unstable) latest changes from the tip of `main` rather than the latest release, use:
+```bash
+brew install ion-cli --HEAD
+```
+
 ### via `cargo`
 
 The `ion-cli` can also be installed by using Rust's package manager, `cargo`.
@@ -177,52 +182,6 @@ 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) of `ion-cli`, run:
-
-```bash
-brew install ion-cli --HEAD
-```
-
-Then make sure that `~/.cargo/bin` is on your `$PATH`. You can confirm that it
-has been installed successfully by running:
-
-```shell
-ion help
-```
-
-You should see output that resembles the following:
-
-```
-A collection of tools for working with Ion data.
-
-Usage: ion [OPTIONS] <COMMAND>
-
-Commands:
-  cat        Prints all Ion input files to the specified output in the requested format.
-  count      (UNSTABLE) Prints the number of top-level values found in the input stream.
-  from       'from' is a namespace for commands that convert other data formats to Ion.
-  generate   (UNSTABLE) Generates code using given schema file.
-  head       Prints the specified number of top-level values in the input stream.
-  inspect    Displays hex-encoded binary Ion alongside its equivalent text Ion.
-                 Its output prioritizes human readability and is likely to change
-                 between versions. Stable output for programmatic use cases is a
-                 non-goal.
-  primitive  (UNSTABLE) Prints the binary representation of an Ion encoding primitive.
-  schema     The 'schema' command is a namespace for commands that are related to Ion Schema.
-  symtab     'symtab' is a namespace for commands that operate on symbol tables
-  to         'to' is a namespace for commands that convert Ion to another data format.
-  help       Print this message or the help of the given subcommand(s)
-
-Options:
-  -h, --help      Print help
-  -V, --version   Print version
-  -X, --unstable  Opt in to using an unstable feature of Ion CLI.
-```
-
 ## Build instructions
 
 ### From source