fix redirects and broken links

README.md

@@ -187,7 +187,7 @@ See also [A comparison of operating systems written in Rust](https://github.com/
 
 * [redox-os/redox](https://github.com/redox-os/redox) — [<img   src="https://api.travis-ci.org/redox-os/redox.svg?branch=master">](https://travis-ci.org/redox-os/redox)
 * [thepowersgang/rust_os](https://github.com/thepowersgang/rust_os) — [<img src="https://api.travis-ci.org/thepowersgang/rust_os.svg?branch=master">](https://travis-ci.org/thepowersgang/rust_os)
-* [helena-project/tock](https://github.com/helena-project/tock) — A secure embedded operating system for Cortex-M based microcontrollers
+* [tock/tock](https://github.com/tock/tock) — A secure embedded operating system for Cortex-M based microcontrollers
 
 ### System tools
 
@@ -245,7 +245,7 @@ See also [A comparison of operating systems written in Rust](https://github.com/
 * [dan-t/rusty-tags](https://github.com/dan-t/rusty-tags) — create ctags/etags for a cargo project and all of its dependencies [<img src="https://api.travis-ci.org/dan-t/rusty-tags.svg?branch=master">](https://travis-ci.org/dan-t/rusty-tags)
 * [frewsxcv/crate-deps](https://github.com/frewsxcv/crate-deps) — generates images of dependency graphs for crates hosted on crates.io
 * [git-journal](https://github.com/saschagrunert/git-journal/) — The Git Commit Message and Changelog Generation Framework [<img src="https://api.travis-ci.org/saschagrunert/git-journal.svg?branch=master">](https://travis-ci.org/saschagrunert/git-journal)
-* [killercup/rustfix](https://github.com/killercup/rustfix)  — automatically applies the suggestions made by rustc [<img src="https://api.travis-ci.org/killercup/rustfix.svg?branch=master">](https://travis-ci.org/killercup/rustfix)
+* [rust-lang-nursery/rustfix](https://github.com/rust-lang-nursery/rustfix)  — automatically applies the suggestions made by rustc [<img src="https://api.travis-ci.org/killercup/rustfix.svg?branch=master">](https://travis-ci.org/killercup/rustfix)
 * [just](https://github.com/casey/just) — A handy command runner for project-specific tasks [<img src="https://api.travis-ci.org/casey/just.svg?branch=master">](https://travis-ci.org/casey/just)
 * [Module Linker](http://fiatjaf.alhur.es/module-linker/#/rust) — Extension that adds `<a>` links to references in `mod`, `use` and `extern crate` statements at GitHub.
 * [ptags](https://github.com/dalance/ptags) — A parallel universal-ctags wrapper for git repository [![Build Status](https://api.travis-ci.org/dalance/ptags.svg?branch=master)](https://travis-ci.org/dalance/ptags)
@@ -1069,7 +1069,7 @@ See also [Are we web yet?](http://www.arewewebyet.org) and [Rust web framework c
 ## Resources
 
 * Benchmarks
-  * [TeXitoi/benchmarksgame-rs](https://github.com/TeXitoi/benchmarksgame-rs) — Rust implementations for the [The Computer Language Benchmarks Game](http://benchmarksgame.alioth.debian.org/) [<img src="https://api.travis-ci.org/TeXitoi/benchmarksgame-rs.svg?branch=master">](https://travis-ci.org/TeXitoi/benchmarksgame-rs)
+  * [TeXitoi/benchmarksgame-rs](https://github.com/TeXitoi/benchmarksgame-rs) — Rust implementations for the [The Computer Language Benchmarks Game](https://benchmarksgame-team.pages.debian.net/benchmarksgame/) [<img src="https://api.travis-ci.org/TeXitoi/benchmarksgame-rs.svg?branch=master">](https://travis-ci.org/TeXitoi/benchmarksgame-rs)
 * Decks & Presentations
   * [Learning systems programming with Rust](https://speakerdeck.com/jvns/learning-systems-programming-with-rust) — Presented by [Julia Evans](https://twitter.com/@b0rk) @ Rustconf 2016.
   * [Shipping a Solid Rust Crate](https://www.youtube.com/watch?v=t4CyEKb-ywA) — Presented by [Michael Gattozzi](https://github.com/mgattozzi) @ RustConf 2017
@@ -1079,10 +1079,10 @@ See also [Are we web yet?](http://www.arewewebyet.org) and [Rust web framework c
   * [exercism.io](http://exercism.io/languages/rust/about) — programming exercises that help you learn new concepts in Rust.
   * [Idiomatic Rust](https://github.com/mre/idiomatic-rust) —  A peer-reviewed collection of articles/talks/repos which teach idiomatic Rust.
   * [Learning Rust With Entirely Too Many Linked Lists](http://cglab.ca/~abeinges/blah/too-many-lists/book/) — in-depth exploration of Rust's memory management rules, through implementing a few different types of list structures.
-  * [Rust by Example](https://rustbyexample.com/)
+  * [Rust by Example](https://doc.rust-lang.org/rust-by-example/)
   * [Rust Cookbook](https://rust-lang-nursery.github.io/rust-cookbook/) — a collection of simple examples that demonstrate good practices to accomplish common programming tasks, using the crates of the Rust ecosystem.
   * [rust-learning](https://github.com/ctjhoa/rust-learning) — a collection of useful resources to learn Rust
-  * [Rustlings](https://github.com/carols10cents/rustlings) — small exercises to get you used to reading and writing Rust code
+  * [Rustlings](https://github.com/rustlings/rustlings) — small exercises to get you used to reading and writing Rust code
   * [stdx](https://github.com/brson/stdx) — Learn these crates first as an extension to std
   * [University of Pennsylvania's Comp Sci Rust Programming Course](http://cis198-2016s.github.io/schedule/)
 * Podcasts