Add Go as an embedding to the book (#1481)

* Add Go as an embedding to the book

Also take this time to list out all embeddings in the README of wasmtime
itself.

docs/SUMMARY.md

@@ -26,9 +26,11 @@
     - [Debugging](./examples-c-debugging.md)
     - [Using multi-value](./examples-c-multi-value.md)
 - [Using WebAssembly from your lanugage](./lang.md)
+  - [Rust](./lang-rust.md)
+  - [C](./lang-c.md)
   - [Python](./lang-python.md)
   - [.NET](./lang-dotnet.md)
-  - [Rust](./lang-rust.md)
+  - [Go](./lang-go.md)
   - [Bash](./lang-bash.md)
 - [Using the `wasmtime` CLI](./cli.md)
   - [Installation](./cli-install.md)
@@ -39,9 +41,6 @@
   - [C/C++](./wasm-c.md)
   - [WebAssembly Text Format (`*.wat`)](./wasm-wat.md)
   - [Example: Markdown Parser](./wasm-markdown.md)
-- [Embedding Wasmtime](embed.md)
-  - [Rust API](./embed-rust.md)
-  - [C/C++ API](./embed-c.md)
 - [Stability](stability.md)
   - [Release Process](./stability-release.md)
   - [Platform Support](./stability-platform-support.md)