Added "Free rust Ebook" (#9046)

* added free rust ebook

* Update books/free-programming-books-langs.md

Co-authored-by: Sharan J <[email protected]>

* updated url to link directly to pdf

Co-authored-by: Sharan J <[email protected]>

Author: gregE21

books/free-programming-books-langs.md

@@ -2220,6 +2220,7 @@ That section got so big, we decided to split it into its own file, the [BY SUBJE
 * [From JavaScript to Rust ebook](https://github.com/wasmflow/node-to-rust/raw/HEAD/from-javascript-to-rust.pdf) - Jarrod Overson (PDF)
 * [Guide to Rustc Development](https://rustc-dev-guide.rust-lang.org)
 * [Learn Rust With Entirely Too Many Linked Lists](https://rust-unofficial.github.io/too-many-lists) - Alexis Beingessner
+* [Learning Rust Ebook](https://riptutorial.com/Download/rust.pdf) - StackOverflow Contributors (PDF)
 * [Rust by Example](https://doc.rust-lang.org/stable/rust-by-example)
 * [Rust Cookbook](https://rust-lang-nursery.github.io/rust-cookbook)
 * [Rust for Rubyists](https://web.archive.org/web/20190520171322/http://www.rustforrubyists.com/book) - Steve Klabnik