chore(bb readme): Add installation instructions and TODOs (#7601)

# Summary

Updating bb's README:
- Add `bb` installation instructions
- Steps toward
#7511 and
#7600

barretenberg/cpp/src/barretenberg/bb/readme.md

@@ -1,16 +1,66 @@
 # BB
 
-## Why is this needed?
+### Why is this needed?
 
 Barretenberg is a library that allows one to create and verify proofs. One way to specify the circuit that one will use to create and verify
 proofs over is to use the Barretenberg standard library. Another way, which pertains to this module is to supply the circuit description using 
-an IR called [ACIR](https://github.com/noir-lang/acvm). This binary will take as input ACIR and witness values described in the IR to create proofs.
+an IR called [ACIR](https://github.com/noir-lang/acvm).
 
+This binary will take as input ACIR and witness values described in the IR to create proofs.
 
-## FilePath vs Stdout
+### Installation
+
+1. Install `bbup` the installation script by running this in your terminal:
+
+    ```bash
+    curl -L https://raw.githubusercontent.com/AztecProtocol/aztec-packages/master/barretenberg/cpp/installation/install | bash
+    ```
+
+2. Reload your terminal shell environment:
+
+    macOS:
+    ```bash
+    source ~/.zshrc
+    ```
+
+    Linux:
+    ```bash
+    source ~/.bashrc
+    ```
+
+3. Install the version of `bb` compatible with your Noir version:
+
+    ```bash
+    bbup -v 0.46.1
+    ```
+
+4. Check if the installation was successful:
+
+    ```bash
+    bb --version
+    ```
+
+If installation was successful, the command would print the version of `bb` installed.
+
+### Usage
+
+TODO: https://github.com/AztecProtocol/aztec-packages/issues/7600
+
+Full list of available commands:
+https://github.com/AztecProtocol/aztec-packages/blob/840486e5ce6b41d6c873239de108b3731dd81101/barretenberg/cpp/src/barretenberg/bb/main.cpp#L1290-L1414
+
+#### FilePath vs Stdout
 
 For commands which allow you to send the output to a file using `-o {filePath}`, there is also the option to send the output to stdout by using `-o -`.
 
-## Maximum Circuit Size
+### Version compatibility with Noir
+
+TODO: https://github.com/AztecProtocol/aztec-packages/issues/7511
+
+For quick reference:
+- Noir v0.32.0 <> BB v0.46.1
+- Noir v0.31.0 <> BB v0.41.0
+
+### Maximum circuit size
 
-Currently the binary downloads an SRS that can be used to prove the maximum circuit size. This maximum circuit size parameter is a constant in the code and has been set to $2^{23}$ as of writing. This maximum circuit size differs from the maximum circuit size that one can prove in the browser, due to WASM limits.
+Currently the binary downloads an SRS that can be used to prove the maximum circuit size. This maximum circuit size parameter is a constant in the code and has been set to $2^{23}$ as of writing. This maximum circuit size differs from the maximum circuit size that one can prove in the browser, due to WASM limits.