Add Contributing page

Contributing.md

@@ -0,0 +1,19 @@
+# Contributing
+
+I (Andrew Belt) generally do not accept external contributions to the Rack codebase itself.
+
+Before writing a single line of code, most features and bug fixes require
+- research to devise the best solution with a convincing argument
+- testing on relevant platforms, audio/MIDI devices, different plugins, etc.
+- dedication to maintain the code in the future
+- generalizability to solve similar issues, and flexibility for solving future solutions without an entire rewrite
+- sometimes legal review
+
+Instead, there are many other areas where contributions are much appreciated.
+- Dependencies of Rack. Especially [nanovg](https://github.com/memononen/nanovg)'s performance, [rtaudio](https://github.com/thestk/rtaudio)/[rtmidi](https://github.com/thestk/rtmidi)'s stability and compatibility, and maybe even touch support in [GLFW](https://github.com/glfw/glfw). You would be helping many more projects than just Rack.
+- your own or others' Rack [plugins](PluginDevelopmentTutorial.md)
+- Maintaining the VCV community plugin database. Volunteer at https://github.com/VCVRack/community/issues/248.
+- Edits to the [VCV Rack manual](https://github.com/VCVRack/manual).
+
+I will consider your contribution to Rack if you first open a [GitHub issue](https://github.com/VCVRack/Rack/issues) with a detailed design proposal, which may create an open discussion before the change is implemented.
+By submitting code through a pull request, you agree to assign the copyright of your code to Andrew Belt to be licensed under the BSD-3-Clause (see [Licenses](https://github.com/VCVRack/Rack#licenses)).

Introduction.md

@@ -22,4 +22,5 @@ Edit this manual at https://github.com/VCVRack/manual.
 - Patchstorage: https://patchstorage.com/platform/vcv-rack/
 - Discord: https://discord.gg/wxa89Mh
 - Reddit: https://www.reddit.com/r/vcvrack/
+- Twitch: https://www.twitch.tv/communities/vcvrackcommunity
 - IRC: http://freenode.net/ #VCVRack

QuickStart.md

@@ -4,12 +4,12 @@ Once Rack is installed and launched *(see [Installing](Installing.html))*, you w
 
 ![Initial patch](images/initialpatch.png)
 
-Add a module by right-clicking on an empty space on the rack, or simply press `<enter>`.
-Select the [Core](Core.html) plugin and then Audio to connect Rack to an audio output on your computer.
+Add a module by right-clicking on an empty space on the rack or by pressing `<enter>`.
+Select the [Core](Core.html) plugin and then Audio to connect Rack to an audio device on your computer.
 
 ![Module Browser](images/modulebrowser.png)
 
-You can move the module around the rack by clicking and dragging an empty space on its panel.
+You can move the module by clicking and dragging an empty space on its panel.
 Select an audio driver and device by clicking on Audio's digital display.
 
 ![Audio interface patch](images/audiopatch.png)

TOC.md

@@ -14,8 +14,8 @@
 - [DSP](DSP.md)
 
 ### Rack Development
+- [Contributing](Contributing.md)
 - [ABI/API Version](Version.md)
-- Contributing (TODO)
 
 ---