Documentation - Repository Structure Explanation in README.md

[jhidalgocarrio]

Hi @Solonets,

Thanks again for this great work. I see the repository is extensive and well structured.

Could you please add in the main README.md a short explanation of what is what? In general, for the whole repo and, in particular, the src folder. For example (as a suggestion), create a simple tree (I used tree -L 2) and write a few lines about what is in there from the conceptual point of view. Such as:

── agent -> this is for bla bla bla
│   ├── CMakeLists.txt
│   ├── include
│   └── src
├── application -> this is the main program for the applications
│   ├── CMakeLists.txt
│   ├── dsopp_main.cpp
│   ├── tools
│   ├── track2trajectory.cpp
│   └── viewer_main.cpp
├── CMakeLists.txt
├── common - > common libraries and utils
│   ├── CMakeLists.txt -> cmake file
│   ├── constexpr_tools -> this is for bla bla
│   ├── fabric_tools -> this is for bla bla
│   ├── file_tools
│   ├── image_tools
│   ├── include
│   ├── patch
│   ├── pattern
│   ├── semantics
│   ├── time
│   └── timestamp_storage
├── dsopp
│   ├── CMakeLists.txt
│   ├── include
│   └── src
├── energy
│   ├── camera_model
│   ├── CMakeLists.txt
│   ├── epipolar_geometry
│   ├── motion
│   ├── n_point_solvers
│   ├── problems
│   └── projector
├── feature_based_slam
│   ├── CMakeLists.txt
│   ├── features
│   ├── initialization_strategy
│   ├── track
│   └── tracker
├── features
│   ├── CMakeLists.txt
│   ├── include
│   ├── internal
│   └── src
├── marginalization
│   ├── CMakeLists.txt
│   ├── include
│   └── src
├── measures
│   ├── CMakeLists.txt
│   └── include
├── output
│   ├── CMakeLists.txt
│   ├── output_interfaces
│   ├── persistent
│   └── visualizer
├── ransac
│   ├── CMakeLists.txt
│   └── include
├── sanity_checker
│   ├── CMakeLists.txt
│   ├── include
│   └── src
├── sensors
│   ├── camera
│   ├── camera_calibration
│   ├── camera_providers
│   ├── camera_transformers
│   ├── CMakeLists.txt
│   ├── sensor
│   ├── sensors
│   └── sensors_builder
├── storage
│   ├── CMakeLists.txt
│   ├── include
│   ├── proto
│   └── src
├── synchronizer
│   ├── CMakeLists.txt
│   ├── include
│   └── src
├── track
│   ├── CMakeLists.txt
│   ├── connections
│   ├── export
│   ├── frames
│   ├── landmarks
│   └── track
└── tracker
├── CMakeLists.txt
├── depth_estimators
├── keyframe_strategy
├── landmarks_activator
└── tracker

In my opinion this will help potential contributors to extend your work. You might instead write it in here if you prefer to do so.