[Update] update lib document (#30)

Author: mistricky

core/src/lib.rs

@@ -1,28 +1,25 @@
 //! CodeSnap is a tool to generate beautiful snapshots of your code snippets. It's a pure Rust library
 //! that provides a simple API to create snapshots of code snippets with syntax highlighting, line
-//! numbers, and custom themes.
+//! numbers, code theme and more.
 //!
-//! # Quick start
+//! ## Quick start
 //!
 //! ```rust
 //! CodeSnap::default()
-//!   .code(
-//!       CodeBuilder::default()
-//!           .language("rust")
-//!           .content(CODE_SNIPPET)
-//!           .build()?,
-//!   )
-//!   .watermark(WatermarkBuilder::default().content("CodeSnap").build()?)
-//!   .build()?
-//!   .create_snapshot()?
-//!   .copy()
+//!     .code(
+//!         CodeBuilder::default()
+//!             .language("haskell")
+//!             .content(r#"print "Hello, CodeSnap!""#)
+//!             .build()?,
+//!     )
+//!     .watermark(WatermarkBuilder::default().content("YYM").build()?)
+//!     .build()?
+//!     .create_snapshot()?
+//!     .raw_data()?
+//!     .copy()?;
 //! ```
 //!
-//! Now try to paste the code snapshot to your friends!
-//!
-//!  /\_/\
-//! ( -.- )  If you enjoy CodeSnap, also try [Silicon](https://github.com/Aloxaf/silicon)
-//!
+//! Now try to paste the code snapshot to your friends! (Don't forget tell him that this was generated by CodeSnap! ^ ^)
 
 mod components;
 pub mod config;