Update optimize contracts section (#310)

* Update hello-world.mdx

* Update hello-world.mdx

* don't need to manually install wasm-opt via binaryen

* remove the -Z flags

docs/getting-started/hello-world.mdx

@@ -344,84 +344,24 @@ The following output should appear.
 ["Hello", "friend"]
 ```
 
-[Write a Contract]: #write-a-contract
-[Deploy to a Local Network]: deploy-to-a-local-network
-[Build]: #build
-[`soroban-cli`]: ../getting-started/setup#install-the-soroban-cli
-
 ## Optimizing Builds
 
-Building optimized contracts to be as small as possible requires some additional tools, and requires installing the `nightly` Rust toolchain and `wasm-opt`.
-
-:::tip
-
-Building optimized contracts is only necessary when deploying to a network with fees or when analyzing and profiling a contract to get it as small as possible. If you're just starting out writing a contract, these steps are not necessary. See [Build] for details on how to build for development.
-
-:::
-
-[Build]: #build
-
-### Install Rust `nightly`
-
-To install the nightly Rust toolchain use [`rustup`].
-
-[`rustup`]: ../getting-started/setup#install-rust
+Use `soroban contract optimize` to further minimize the size of the `.wasm`.
 
 ```sh
-rustup install nightly
-rustup target add --toolchain nightly wasm32-unknown-unknown
-rustup component add --toolchain nightly rust-src
+soroban contract optimize \
+    --wasm target/wasm32-unknown-unknown/release/first_project.wasm
 ```
 
-### Install `wasm-opt`
-
-To install `wasm-opt`, install [`binaryen`]. Depending on your operating system there may be different ways to install it.
-
-[`binaryen`]: https://github.com/WebAssembly/binaryen
+This will optimize and output a new `first_project.optimized.wasm` file in the same location as the input `.wasm`.
 
-<Tabs>
-<TabItem value="macos" label="macOS" default>
-
-```sh
-brew install binaryen
-```
-
-</TabItem>
-<TabItem value="linux" label="Linux">
-
-For distributions that use `apt`:
-
-```sh
-sudo apt install binaryen
-```
-
-For other distributions see:
-https://github.com/WebAssembly/binaryen/releases
-
-</TabItem>
-<TabItem value="windows" label="Windows">
-
-For install options see: https://github.com/WebAssembly/binaryen/releases
-
-</TabItem>
-</Tabs>
-
-### Build with `nightly` and `wasm-opt`
-
-Build your contract using nightly. The additional options instruct the compiler to remove unnecessary information from the contract.
+:::tip
 
-```sh
-cargo +nightly build \
-    --target wasm32-unknown-unknown \
-    --release \
-    -Z build-std=std,panic_abort \
-    -Z build-std-features=panic_immediate_abort
-```
+Building optimized contracts is only necessary when deploying to a network with fees or when analyzing and profiling a contract to get it as small as possible. If you're just starting out writing a contract, these steps are not necessary. See [Build] for details on how to build for development.
 
-Use `wasm-opt` to further minimize the size of the `.wasm`.
+:::
 
-```sh
-wasm-opt -Oz \
-    target/wasm32-unknown-unknown/release/first_project.wasm \
-    -o target/wasm32-unknown-unknown/release/first_project_optimized.wasm
-```
+[Write a Contract]: #write-a-contract
+[Deploy to a Local Network]: deploy-to-a-local-network
+[Build]: #build
+[`soroban-cli`]: ../getting-started/setup#install-the-soroban-cli