docs: Fixed link and typo (#3151) [ci skip]

fixed broken links and typos, added feature links

.github/CONTRIBUTING.md

@@ -75,10 +75,10 @@ Follow these steps to get going.  If you are having trouble, don't be afraid to
 *Excellent.*  Here's how:
 
 - **Handy with JavaScript?**  Please check out the issues labeled [`help-wanted`](https://github.com/mochajs/mocha/issues?utf8=%E2%9C%93&q=is%3Aissue+is%3Aopen+label%3Ahelp-wanted).
-- **Can you write good (and do other stuff good too)?**  Help with the documentation.  See the [0issues for our site](https://github.com/mochajs/mocha/issues?q=is%3Aopen+is%3Aissue+label%3Adocumentation).
+- **Can you write good (and do other stuff good too)?**  Help with the documentation.  See the [issues for our site](https://github.com/mochajs/mocha/issues?q=is%3Aopen+is%3Aissue+label%3Adocumentation).
 - **Design your thing?**  [Our site](https://github.com/mochajs/mocha/tree/master/docs) needs your magic touch.
 - **Know Mocha's codebase?**  We could use your help triaging issues and/or reviewing pull requests.  Please contact an [org member](https://github.com/orgs/mochajs/people), and we'll chat.
 - **Want to build our community?**  Mocha has a *lot* of users.  We could use your help bringing everyone together in peace and harmony.  Please contact an [org member](https://github.com/mochajs/people).
-- **You can sell dirt to worms?**  Let's raise Mocha's profile in the JavaScript and OSS communities.  Please contact an [org member](https://github.com/mochajs/people)!
+- **You can sell dirt to worms?**  Let's raise Mocha's profile in the JavaScript and OSS communities.  Please contact an [org member](https://github.com/orgs/mochajs/people)!
 - **Wait--you write unit tests for *fun*?**  A PR which increases coverage is unlikely to be turned down.
 - **Are you experienced?**  If you're a seasoned Mocha user, why not help answer some questions in the [chat room](https://gitter.im/mochajs/mocha)?

docs/index.md

@@ -13,36 +13,36 @@ Mocha is a feature-rich JavaScript test framework running on [Node.js](http://no
 
 ## Features
 
-- browser support
-- simple async support, including promises
-- test coverage reporting
-- string diff support
-- javascript API for running tests
+- [browser support](#running-mocha-in-the-browser)
+- [simple async support, including promises](#asynchronous-code)
+- [test coverage reporting](#wallabyjs)
+- [string diff support](#diffs)
+- [javascript API for running tests](#more-information)
 - proper exit status for CI support etc
-- auto-detects and disables coloring for non-ttys
-- maps uncaught exceptions to the correct test case
-- async test timeout support
-- test retry support
-- test-specific timeouts
-- growl notification support
-- reports test durations
-- highlights slow tests
-- file watcher support
-- global variable leak detection
-- optionally run tests that match a regexp
-- auto-exit to prevent "hanging" with an active loop
-- easily meta-generate suites & test-cases
-- mocha.opts file support
-- clickable suite titles to filter test execution
-- node debugger support
+- [auto-detects and disables coloring for non-ttys](#reporters)
+- [maps uncaught exceptions to the correct test case](#browser-specific-methods)
+- [async test timeout support](#delayed-root-suite)
+- [test retry support](#retry-tests)
+- [test-specific timeouts](#test-level) 
+- [growl notification support](#mochaopts)
+- [reports test durations](#test-duration)
+- [highlights slow tests](#dot-matrix)
+- [file watcher support](#min) 
+- [global variable leak detection](#--check-leaks) 
+- [optionally run tests that match a regexp](#-g---grep-pattern) 
+- [auto-exit to prevent "hanging" with an active loop](#--exit----no-exit)
+- [easily meta-generate suites](#markdown) & [test-cases](#list)
+- [mocha.opts file support](#mochaopts)
+- clickable suite titles to filter test execution  
+- [node debugger support](#-d---debug)
 - detects multiple calls to `done()`
-- use any assertion library you want
-- extensible reporting, bundled with 9+ reporters
-- extensible test DSLs or "interfaces"
-- before, after, before each, after each hooks
-- arbitrary transpiler support (coffee-script etc)
-- TextMate bundle
-- and more!
+- [use any assertion library you want](#assertions)
+- [extensible reporting, bundled with 9+ reporters](#reporters)
+- [extensible test DSLs or "interfaces"](#interfaces)
+- [before, after, before each, after each hooks](#hooks)
+- [arbitrary transpiler support (coffee-script etc)](#--compilers)
+- [TextMate bundle](#textmate)
+- [and more!](https://mochajs.org)
 
 ## Table of Contents