Created sub READMEs for CLI only version

Sub READMEs contain the relevant resources from the main
README of the web version. All second edition Rust Book links
were updated to the 2018 edition.

Fixed to typos in main README.md.

README.md

@@ -1,6 +1,6 @@
 # rustlings
 
-Greetings and welcome to rustlings. This project contains small exercises get you used to reading and writing code. This includes reading and responding to compiler messages!
+Greetings and welcome to rustlings. This project contains small exercises to get you used to reading and writing code. This includes reading and responding to compiler messages!
 
 ## How to get started
 To use rustlings you have to have [rust](https://www.rust-lang.org/) installed on your machine.
@@ -13,12 +13,12 @@ by running `cargo install --path <path to the rustlings repo>`
 (NOTE: for rustling to function you have to be in the directory of the repo).
 
 ## Doing exercises
-The execises are sorted by topic and can be found in the subdirectory `rustlings/exercises/<topic>`. For every topic there is an additional README file with some reasources to get you started on the topic. We really recommend, that you have a look at them before you start. 
+The exercises are sorted by topic and can be found in the subdirectory `rustlings/exercises/<topic>`. For every topic there is an additional README file with some resources to get you started on the topic. We really recommend, that you have a look at them before you start. 
 
 Your task is simple every exercise contains an error you have to solve, in order to make it compile. 
 
 Running rustlings with the subcommand `verify` will compile every exercise in the recommended order. It will stop at the first exercise that didn't compile and show you the error to be solved.
 
-If you want to run a single erxercise you can use the subcommand `run <path to the exercise>`.
+If you want to run a single exercise, you can use the subcommand `run <path to the exercise>`.
 
-When you struggle to solve the error, there is usually a tip at the bottom of the each exercise. 
+When you struggle to solve the error, there is usually a tip at the bottom of each exercise. 

exercises/error_handling/README.md

@@ -0,0 +1,5 @@
+For this exercise check out the chapters:
+- [Error Handling](https://doc.rust-lang.org/book/second-edition/ch09-02-recoverable-errors-with-result.html) 
+- [Generics](https://doc.rust-lang.org/book/second-edition/ch10-01-syntax.html) 
+
+of the Rust Book.

exercises/functions/REAMDE.md

@@ -0,0 +1 @@
+For this exercise check out the chapter [Functions](https://doc.rust-lang.org/book/second-edition/ch03-03-how-functions-work.html) of the Rust Book.

exercises/if/REAMDE.md

@@ -0,0 +1 @@
+For this exercise check out the chapter [If](https://doc.rust-lang.org/book/second-edition/ch03-05-control-flow.html) of the Rust Book.

exercises/macros/README.md

@@ -0,0 +1,2 @@
+For this exercise check out the section [Macros](https://doc.rust-lang.org/book/first-edition/macros.html) and the chapter
+[Macros Appendix](https://doc.rust-lang.org/book/2018-edition/appendix-04-macros.html) of the Rust Book and [The Little Book of Rust Macros](https://danielkeep.github.io/tlborm/book/index.html). 

exercises/modules/README.md

@@ -0,0 +1 @@
+For this exercise check out the [Modules](https://doc.rust-lang.org/book/second-edition/ch07-01-mod-and-the-filesystem.html) chapter of the Rust Book.

exercises/move_semantics/README.md

@@ -0,0 +1,7 @@
+These exercises are adapted from [pnkfelix](https://github.com/rustlings/rustlings/blob/master)'s [Rust Tutorial](https://pnkfelix.github.io/rust-examples-icfp2014/) -- Thank you Felix!!!
+
+For this exercise check out the chapters:
+- [Ownership](https://doc.rust-lang.org/book/second-edition/ch04-01-what-is-ownership.html)
+- [Reference and borrowing](https://doc.rust-lang.org/book/second-edition/ch04-02-references-and-borrowing.ht)
+
+of the Rust Book.

exercises/standard_library_types/README.md

@@ -0,0 +1 @@
+For this exercise check out the chapter [Shared-State Concurrency](https://doc.rust-lang.org/book/second-edition/ch16-03-shared-state.html) of the Rust Book.

exercises/tests/README.md

@@ -0,0 +1,3 @@
+Going out of order from the book to cover tests -- many of the following exercises will ask you to make tests pass!
+
+For this exercise check out the section [How to Write Tests](https://doc.rust-lang.org/book/second-edition/ch11-01-writing-tests.html) of the Rust Book.

exercises/threads/README.md

@@ -0,0 +1 @@
+For this exercise check out the [Dining Philosophers example](https://doc.rust-lang.org/1.4.0/book/dining-philosophers.html) and the chapter [Concurrency](https://doc.rust-lang.org/book/second-edition/ch16-01-threads.html) of the Rust Book.