Add instructions on using the BCR to the README.md

If your project is using Bazel, you can make your builds more reproducible by depending on protobuf through the Bazel Central Registry, instead of building it from source.

Author: Binit SHah

src/README.md

@@ -11,6 +11,53 @@ CMake Installation
 To compile or install protobuf from source using CMake, see
 [cmake/README.md](../cmake/README.md).
 
+C++ Protobuf using the Bazel Central Registry - Unix
+----------------------------------------------------
+
+The C++ Protocol Buffer runtime is available on the [Bazel Central Registry](https://registry.bazel.build/modules/protobuf). If your project uses Bazel, you can simply add `@protobuf//:protobuf` as a dependency. Here's an example setup:
+
+ * main.cpp
+     * ```c
+       #include "<messages>.pb.h"
+       int main() {
+           GOOGLE_PROTOBUF_VERIFY_VERSION;
+           return 0;
+       }
+       ```
+ * \<messages\>.pb.cc/.h
+     * Generated using `protoc`, downloaded from [Github Releases](https://github.com/protocolbuffers/protobuf/releases).
+     * Check the runtime version of the compiler using `protoc --version`. It'll return something like "libprotoc 29.2".
+ * MODULE.bazel
+     * ```
+       bazel_dep(name = "protobuf", version = "29.2")
+       ```
+     * Note that the version matches `protoc`'s version
+ * BUILD
+     * ```
+       cc_library(
+           name = "<messages>",
+           srcs = ["<messages>.pb.cc"],
+           hdrs = ["<messages>.pb.h"],
+           deps = [
+               "@protobuf//:protobuf",
+           ],
+       )
+       cc_binary(
+           name = "main",
+           srcs = ["main.cpp"],
+           deps = [
+               ":<messages>",
+           ],
+       )
+       ```
+ * WORKSPACE
+     * ```
+       workspace(name = "example")
+       ```
+
+Then build it using `bazel build :main` and run the binary using `./bazel-bin/main`
+
+
 C++ Protobuf - Unix
 -----------------------