Miscellaneous doc updates (#1383)

* Add additional links to embedding and tutorial documentation.

* Fix a broken link to CONTRIBUTING.md.

Fixes #1280.

docs/embed-rust.md

@@ -7,7 +7,7 @@ crate][wasmtime] has to offer and the [book examples for
 Rust](./examples-rust-embed.md) for more information.
 
 [apidoc]: https://bytecodealliance.github.io/wasmtime/api/wasmtime/
-[wasmtime]: https://crates.io/crates/wasmtime
+[crate]: https://crates.io/crates/wasmtime
 
 ## Creating the WebAssembly to execute
 

docs/embed.md

@@ -1,3 +1,10 @@
 # Embedding Wasmtime
 
-... more coming soon
+Wasmtime can be used as a library to embed WebAssembly execution support
+within applications. It has a Rust API, and also supports the official
+[WebAssembly C API].
+
+* [Rust](embed-rust.md)
+* [C](embed-c.md)
+
+[WebAssembly C API]: https://github.com/WebAssembly/wasm-c-api

docs/tutorial.md

@@ -1,3 +1,7 @@
 # Tutorial
 
-... more coming soon
+This tutorial walks through creating a simple Hello World WebAssembly program
+and then running it.
+
+* [Creating `hello-world.wasm`](tutorial-create-hello-world.md)
+* [Running `hello-world.wasm`](tutorial-run-hello-world.md)