docs: update installation instructions for crates.io release

Author: sou1118

README.md

@@ -61,22 +61,18 @@ Compile the output with `typst compile` to get a PDF with visual diff markup.
 
 ## Installation
 
-### From source
+### From crates.io
 
 ```sh
-cargo install --git https://github.com/sou1118/typdiff
+cargo install typdiff
 ```
 
-### Build locally
+### From source (latest development version)
 
 ```sh
-git clone https://github.com/sou1118/typdiff
-cd typdiff
-cargo build --release
+cargo install --git https://github.com/sou1118/typdiff
 ```
 
-The binary will be at `target/release/typdiff`.
-
 ## Usage
 
 ```