Move project structure from README.md

docs/Developer-Guide_Overview.md

@@ -40,3 +40,78 @@ Function | Armbian | Yocto | Buildroot |
 | Initramfs support | yes | yes | yes |
 | Getting started | quick | very slow | slow |
 | Cross compilation | yes | yes | yes |
+
+## Framework Structure
+
+```text
+├── cache                                Work / cache directory
+│   ├── aptcache                         Packages
+│   ├── ccache                           C/C++ compiler
+│   ├── docker                           Docker last pull
+│   ├── git-bare                         Minimal Git
+│   ├── git-bundles                      Full Git
+│   ├── initrd                           Ram disk
+│   ├── memoize                          Git status
+│   ├── patch                            Kernel drivers patch
+│   ├── pip                              Python
+│   ├── rootfs                           Compressed userspaces
+│   ├── sources                          Kernel, u-boot and other sources
+│   ├── tools                            Additional tools like ORAS
+│   └── utility
+├── config                               Packages repository configurations
+│   ├── targets.conf                     Board build target configuration
+│   ├── boards                           Board configurations
+│   ├── bootenv                          Initial boot loaders environments per family
+│   ├── bootscripts                      Initial Boot loaders scripts per family
+│   ├── cli                              CLI packages configurations per distribution
+│   ├── desktop                          Desktop packages configurations per distribution
+│   ├── distributions                    Distributions settings
+│   ├── kernel                           Kernel build configurations per family
+│   ├── sources                          Kernel and u-boot sources locations and scripts
+│   ├── templates                        User configuration templates which populate userpatches
+│   └── torrents                         External compiler and rootfs cache torrents
+├── extensions                           Extend build system with specific functionality
+├── lib                                  Main build framework libraries
+│   ├── functions
+│   │   ├── artifacts
+│   │   ├── bsp
+│   │   ├── cli
+│   │   ├── compilation
+│   │   ├── configuration
+│   │   ├── general
+│   │   ├── host
+│   │   ├── image
+│   │   ├── logging
+│   │   ├── main
+│   │   └── rootfs
+│   └── tools
+├── output                               Build artifact
+│   └── deb                              Deb packages
+│   └── images                           Bootable images - RAW or compressed
+│   └── debug                            Patch and build logs
+│   └── config                           Kernel configuration export location
+│   └── patch                            Created patches location
+├── packages                             Support scripts, binary blobs, packages
+│   ├── blobs                            Wallpapers, various configs, closed source bootloaders
+│   ├── bsp-cli                          Automatically added to armbian-bsp-cli package
+│   ├── bsp-desktop                      Automatically added to armbian-bsp-desktopo package
+│   ├── bsp                              Scripts and configs overlay for rootfs
+│   └── extras-buildpkgs                 Optional compilation and packaging engine
+├── patch                                Collection of patches
+│   ├── atf                              ARM trusted firmware
+│   ├── kernel                           Linux kernel patches
+|   |   └── family-branch                Per kernel family and branch
+│   ├── misc                             Linux kernel packaging patches
+│   └── u-boot                           Universal boot loader patches
+|       ├── u-boot-board                 For specific board
+|       └── u-boot-family                For entire kernel family
+├── tools                                Tools for dealing with kernel patches and configs
+└── userpatches                          User: configuration patching area
+    ├── config-example.conf              User: example user config file
+    ├── customize-image.sh               User: script will execute just before closing the image
+    ├── atf                              User: ARM trusted firmware
+    ├── extensions                       User: Extend build system with specific functionality
+    ├── kernel                           User: Linux kernel per kernel family
+    ├── misc                             User: various
+    └── u-boot                           User: universal boot loader patches
+```