docs: add Quick Start build instructions to barretenberg README

barretenberg/README.md

@@ -10,7 +10,7 @@ Barretenberg (or `bb` for short) is an optimized elliptic curve library for the
 
 - [Barretenberg](#barretenberg)
   - [Development](#development)
-    - [Bootstrap](#bootstrap)
+    - [Quick Start](#quick-start)
     - [Build Options and Instructions](#build-options-and-instructions)
       - [WASM build](#wasm-build)
       - [Fuzzing build](#fuzzing-build)
@@ -19,7 +19,6 @@ Barretenberg (or `bb` for short) is an optimized elliptic curve library for the
     - [Testing](#testing)
       - [Integration tests with Aztec in Monorepo](#integration-tests-with-aztec-in-monorepo)
         - [Integration tests with Aztec in Barretenberg Standalone Repo](#integration-tests-with-aztec-in-barretenberg-standalone-repo)
-        - [Testing locally in docker](#testing-locally-in-docker)
     - [Docs Build](#docs-build)
     - [Benchmarks](#benchmarks)
       - [x86\_64](#x86_64)
@@ -92,15 +91,33 @@ git clone -b release/10.x --depth 1 https://github.com/llvm/llvm-project.git \
 
 </details>
 
-### Bootstrap
+### Quick Start
 
-The bootstrap script will build both the native and wasm versions of barretenberg:
+If you just want to use the `bb` binary and don't need to modify the source code, the easiest option is to install a pre-built binary using [bbup](bbup/README.md):
 
 ```bash
-cd cpp
-./bootstrap.sh
+curl -L https://raw.githubusercontent.com/AztecProtocol/aztec-packages/refs/heads/master/barretenberg/bbup/install | bash
+bbup
+bb --version
 ```
 
+To build from source, use the bootstrap script. By default it uses a [Zig](https://ziglang.org/)-wrapped Clang for portable binaries (glibc 2.35+). This requires `zig` to be installed in addition to the dependencies listed above:
+
+```bash
+cd barretenberg/cpp
+./bootstrap.sh               # Full build (native + WASM)
+./bootstrap.sh build_native  # Native only (faster)
+```
+
+If you don't have Zig installed, you can use the `default` preset which only requires a standard Clang toolchain:
+
+```bash
+cd barretenberg/cpp
+NATIVE_PRESET=default ./bootstrap.sh build_native
+```
+
+The resulting binary will be at `build/bin/bb`.
+
 ### Build Options and Instructions
 
 CMake can be passed various build options on its command line:
@@ -237,19 +254,6 @@ CI will automatically run integration tests against Aztec. It is located in the
 
 When working on a PR, you may want to point this file to a different Aztec branch or commit, but then it should probably be pointed back to master before merging.
 
-##### Testing locally in docker
-
-A common issue that arises is that our CI system has a different compiler version e.g. namely for GCC. If you need to mimic the CI operating system locally you can use bootstrap_docker.sh or run dockerfiles directly. However, there is a more efficient workflow for iterative development:
-
-```
-cd barretenberg/cpp
-./scripts/docker_interactive.sh
-mv build build-native # your native build folders are mounted, but will not work! have to clear them
-cmake --preset gcc ;  cmake --build build
-```
-
-This will allow you to rebuild as efficiently as if you were running native code, and not have to see a full compile cycle.
-
 ### Docs Build
 
 If doxygen is installed on the system, you can use the **build_docs** target to build documentation, which can be configured in vscode CMake extension or using