Update README and add project/repo overview doc

Signed-off-by: falkTX <falktx@falktx.com>

README.md

@@ -1,10 +1,71 @@
 # DISTRHO Cardinal
 
-*Cardinal, bring forth the Rack!*
+*Cardinal, the Rack!*
 
-WORK IN PROGRESS - nothing to see here
+**! THIS PROJECT IS A WORK IN PROGRESS !**
 
-Just an experiment to see how far we can go about a VCV plugin version that is opensource and uses original VCV source core directly.
-Maybe it will work, maybe not, hard to say at this point.
+This is a [DPF-based](https://github.com/DISTRHO/DPF/) plugin wrapper around [VCV Rack](https://github.com/VCVRack/Rack/),
+using its code directly instead of forking the project.  
+The target is to have a proper, self-contained, fully free and open-source plugin version of Rack.  
+See [project overview](doc/OVERVIEW.md) document for an overview on how the project source code is structured.
 
-This is a DPF'ied build of [VCVRack](https://github.com/VCVRack/Rack), allowing it to be used as an audio plugin.
+Because it is using DPF, Cardinal already supports LV2 and VST2 with an extra JACK standalone mode if self-compiled.  
+A VST3 version is in progress, already part of the build but still experimental.
+
+**The project should be considered in alpha state at the moment.**
+
+## Current status
+
+Most of the features already work, you can assume things work in general except when stated otherwise.  
+Currently the following features are known NOT to work:
+
+- Clipboard (copy&paste)
+- Clock related triggers in built-in MIDI modules
+- Export/import module selection
+- File dialogs triggered by module right-click menus
+
+### Current builds
+
+If you want to try this out early, checkout the GitHub actions tab.  
+There is absolutely no warranty, use at your own risk and all that...
+
+## Why
+
+Cardinal was created first and foremost as a way to have Rack as a **proper open-source audio plugin**.  
+A proper audio plugin should be self-contained as much as possible, as to not interfere with the DAW/Host.
+Loading external modules clearly goes against this idea.  
+Not to mention being **open-source**, otherwise we are at the mercy of the wishes of a company for what we can and cannot do,
+which is not something Cardinal's authors wish to abide by.
+
+A self-contained plugin can't be overstated, as DLL/shared-object symbol conflicts can trigger hard-to-debug crashes.  
+While Rack tries to mitigate this as much as possible, crashes due to conflicting modules have already been seen in v2 builds.  
+On the other side, Cardinal redefines class and function names as needed to avoid as many conflicts as possible.
+
+Support for ARM and non-mainstream platforms (for example BSD) has also always been missing from the official Rack since the start.  
+While we can patch the Rack free version to support these, same can't be done with VCV Rack Pro with it being a closed-source product.  
+The online library/store only supports a very specific set of platforms too,
+so non-supported platforms would need any 3rd-party modules to be manually compiled to make them usable.
+
+Unhappiness with the audio threading behaviour of Rack also plays a role.  
+Both audio and MIDI should be locked to the host audio thread as to minimize (or even altogether remove) latency and jitter.  
+The use of separate threads for MIDI is bad design, one that has been corrected in DAWs and JACK-MIDI for several years...  
+But Rack's use of RtMidi requires separate threading, so Cardinal does not use it.
+
+Other relevant reasons include:
+
+ - LV2 plugin version from the start
+ - Proper dark mode support
+ - Proper optimized build (because all code is compiled to a single file, we can use LTO over the whole thing)
+ - Removing online access from the plugin and included modules (no phone-home here!)
+ - Works as a test case for [DPF](https://github.com/DISTRHO/DPF/) and [Carla](https://github.com/falkTX/Carla/)
+ - It is fun :)
+
+## Vs. Rack Pro
+
+It needs to be said that Cardinal project and its author(s) do not wish anything bad to the original/official Rack project.  
+In fact, Cardinal wouldn't exist if not for Rack v2 release. (which has many needed things to make a plugin version work)
+
+Cardinal and Rack should be able to co-exist friendly and peacefully, as they clearly have different targets.  
+It is likely most people will prefer to use Rack Pro for its official support and its big module collection (including commercial ones).
+
+A feature comparison between Cardinal and Rack Pro can be seen [here](doc/DIFFERENCES.md).