Plugin Wasmtime: Docs for C & C++ plugins

- Add documentation for writing C and C++ plugins to run with rust hosts
  using wasmtime component-model

developer/src/SUMMARY.md

@@ -17,6 +17,7 @@
         - [Advantages](plugin/wasmtime/advantages.md)
         - [Disadvantages](plugin/wasmtime/disadvantages.md)
         - [Notes & Tips](plugin/wasmtime/notes-tips.md)
+        - [Multi-Language Plugins](plugin/wasmtime/multi-language.md)
         - [Plugin Proposal](plugin/wasmtime/proposal.md) 
             - [Parser](plugin/wasmtime/proposal-parser.md) 
             - [Source](plugin/wasmtime/proposal-source.md) 

developer/src/plugin/wasmtime/multi-language.md

@@ -0,0 +1,62 @@
+# Multi-Language Plugins
+
+With WASM, it's possible to write plugins in any language that compiles to WebAssembly and supports the component model.
+Many languages support WebAssembly and can be compiled to WASM modules, then with tools like [wasm-tools](https://github.com/bytecodealliance/wasm-tools), it can be possible to create components from them, producing WASM-components files that can be loaded and validated by `wasmtime` host.
+
+## C & C++
+
+Writing plugins in C or C++ can be done using the following steps and tools:
+
+### 1. Code Generation & Bindgen
+
+[wit-bindgen CLI tool](https://github.com/bytecodealliance/wit-bindgen#cli-installation) can be used to generate all functions and types form a `wit` file with the command:
+
+```bash
+wit-bindgen c {PATH_TO_WIT_FILE}
+# Generating "host.c"
+# Generating "host.h"
+# Generating "host_component_type.o"
+```
+
+This command will generate `*.h`, `*.c`, and `*.o` files from the `wit` file, which can be included in C or C++ code.
+For example, we created the file `my-component.c` and included the host header files in it to use the types and functions from the host, providing the needed functions from the plugin:
+
+```c
+// Generated header from wit-bindgen command 
+#include "host.h"
+
+void host_run() {
+  // Calling function on the host 
+  host_print(&my_string);
+  //...
+}
+```
+
+### 2. Compiling as WASM Component
+
+C and C++ code can be compiled for the wasm32-wasi target using the [WASI SDK](https://github.com/webassembly/wasi-sdk) project. 
+`WASI SDK` provides `clang` binaries in their releases, which are pre-configured to compile to WebAssembly. These binaries can be downloaded from their release pages and used directly to compile:
+
+```bash
+# The `clang` command here should be the binary from `WASI SDK` releases.
+clang host.c host_component_type.o my-component.c -o my-core.wasm -mexec-model=reactor
+```
+
+This command will create the file `my-core.wasm`, which we need to convert to a WASM component using the [wasm-tools CLI](https://github.com/bytecodealliance/wasm-tools) to create a new WASM component based on the created WASM module:
+
+```bash
+wasm-tools component new ./my-core.wasm -o my-component.wasm
+```
+
+We can use `wasm-tools` to inspect the output binary:
+```bash
+wasm-tools component wit ./my-component.wasm
+```
+
+The created `my-component.wasm` file can be used and validate by a `wasmtime` Rust host.
+
+### References & Links:
+
+- [wasi-sdk](https://github.com/webassembly/wasi-sdk).
+- [wit-bindgen](https://github.com/bytecodealliance/wit-bindgen?tab=readme-ov-file#guest-cc).
+- [wasm-tools](https://github.com/bytecodealliance/wasm-tools).