[doc] Add some documentation for debugging

The previous documentation only covers how to enable debug info when
embedding Wasmtime. This change should cover the commonly-asked
question: how do I debug in Wasmtime?

docs/examples-debugging.md

@@ -0,0 +1,24 @@
+# Debugging WebAssembly
+
+The following steps describe a common way to debug a WebAssembly module in
+Wasmtime:
+
+1. Compile your WebAssembly with debug info enabled, usually `-g`; for
+   example: 
+
+    ```sh
+    clang foo.c -g -o foo.wasm
+    ```
+
+2. Run Wasmtime with the debug info enabled; this is `-g` from the CLI and
+   `Config::debug_info(true)` in an embedding (e.g. see [debugging in a Rust
+   embedding](./examples-rust-debugging.md))
+
+3. Use a supported debugger:
+
+    ```sh
+    lldb -- wasmtime run -g foo.wasm
+    ```
+    ```sh
+    gdb --args wasmtime run -g foo.wasm
+    ```