Renamed readme files properly

exercises/functions/REAMDE.md

@@ -1,7 +0,0 @@
-### Functions
-
-Here, you'll learn how to write functions and how Rust's compiler can trace things way back.
-
-#### Book Sections
-
-- [How Functions Work](https://doc.rust-lang.org/stable/book/ch03-03-how-functions-work.html)

exercises/strings/REAMDE.md

@@ -1,9 +0,0 @@
-### Strings
-
-Rust has two string types, a string slice (`&str`) and an owned string (`String`).
-We're not going to dictate when you should use which one, but we'll show you how
-to identify and create them, as well as use them.
-
-#### Book Sections
-
-- [Strings](https://doc.rust-lang.org/stable/book/ch08-02-strings.html)