docs(book): fixed dependency versions in docs

Also added instruction for installing the Wasm target.

Closes #79.

docs/0.3.x/en-US/hello-world.md

@@ -61,7 +61,9 @@ Finally, we tell Perseus what to do if something in your app fails, like if the
 
 </details>
 
-Now install the Perseus CLI with `cargo install perseus-cli` (you'll need `wasm-pack` to let Perseus build your app, use `cargo install wasm-pack` to install it) to make your life way easier, and deploy your app to <http://localhost:8080> by running `perseus serve` inside the root of your project! This will take a while the first time, because it's got to fetch all your dependencies and build your app.
+Now, tell Rust that you want to be compiling for WebAssembly by adding that platform as a target. You can do this by running `rustup target add wasm32-unknown-unknown`.
+
+After that's finished, you can install the Perseus CLI with `cargo install perseus-cli --version 0.3.0-beta.17` (you'll need `wasm-pack` to let Perseus build your app, use `cargo install wasm-pack` to install it) to make your life way easier, and deploy your app to <http://localhost:8080> by running `perseus serve` inside the root of your project! This will take a while the first time, because it's got to fetch all your dependencies and build your app.
 
 <details>
 <summary>Why do I need a CLI?</summary>

examples/basic/Cargo.toml.example

@@ -6,7 +6,7 @@ edition = "2018"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-perseus = "0.2"
+perseus = "0.3.0-beta.17"
 sycamore = "0.6"
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"

examples/tiny/Cargo.toml.example

@@ -6,5 +6,5 @@ edition = "2018"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-perseus = "0.2"
+perseus = "0.3.0-beta.17"
 sycamore = "0.6"