Write a real, full README with appropriate credits

Author: RedFantom

README.md

@@ -3,6 +3,71 @@
 adds support for SVG image files. Tkinter makes use of Tcl/Tk under the
 hood, and thus can benefit from this addition. Note that SVG support 
 has been included in Tk 8.7 and thus this package can be made obsolete 
-in the future when Python gets distributed with Tk 8.7.
+in the future when Python gets distributed with Tk 8.7. This package is 
+merely a repackaging of the `tksvg` library for Python with a modified
+build system.
 
+## Building and installation
+This package makes use of the same build system as [`gttk`](https://github.com/TkinterEP/python-gttk)
+and other Tcl C-extensions with CMake. This means that on both Windows
+and Linux you will need a working CMake installation that can find the
+Tcl development files. If you wish to build with Visual Studio, you can
+build with the build system of the [upstream](https://github.com/oehhar/tksvg).
 
+### Linux
+Adapt the commands to your specific distribution. The commands given
+here assume Ubuntu 20.04.
+```bash
+sudo apt install cmake build-essential tcl-dev tk-dev python3-tk
+python -m pip install scikit-build
+python setup.py install
+```
+
+### Windows
+Due to the rolling-release type distribution of MSYS, no up-to-date 
+build instructions are provided in this file. Please refer to the 
+AppVeyor build configuration in `.appveyor.yml` to derive the latest 
+build instructions. Some general pointers:
+- The commands assume that you have a working [MSYS2](https://www.msys2.org/)
+  environment. If you do not have this, you'll have to set it up to make 
+  use of the Windows build system.
+- Dependencies of the compiled binaries are detected and found using 
+  [Dependencies](https://github.com/lucasg/Dependencies). Make sure it
+  is available before running the `setup.py install` command.
+- The AppVeyor configuration may have to work around bugs in MSYS that 
+  you might not encounter if you're using a different version. If you're 
+  confused by how the dependencies are installed, simply refer to the
+  list found in [`setup.py`](https://github.com/TkinterEP/python-tksvg/blob/02cf680bf4b9c5471d6bff1508e9705648ef18cd/setup.py#L52).
+  
+## Usage
+Using the library has been made as similar as possible to using a normal
+`tk.PhotoImage`. Simply create an `SvgImage` instance and the `tksvg` 
+library will automatically be loaded for you.
+```python
+import tkinter as tk
+import tksvg
+
+window = tk.Tk()
+svg_image = tksvg.SvgImage(file="tests/orb.svg")
+label = tk.Label(image=svg_image)
+label.pack()
+window.mainloop()
+```
+
+## License & Copyright
+This repository merely provides a version of the original [tksvg](https://github.com/oehhar/tksvg)
+for Python's Tkinter. The package is available under the BSD-like 
+[Tcl License](https://github.com/TkinterEP/python-tksvg/blob/master/LICENSE.md).
+The build system (`setup.py`, `.appveyor.yml` and `.travis.yml`) are 
+available under the terms of [GNU GPLv3](http://www.gnu.org/licenses/gpl-3.0.en.html),
+as any changes to these should be shared under permissive terms so as to
+preserve the possibility of building these packages.
+```
+Copyright (C) 2002-2004 Maxim Shemanarev http://antigrain.com
+Copyright (c) 2013-14 Mikko Mononen [email protected]
+Copyright (c) 2018 Christian Gollwitzer [email protected]
+Copyright (c) 2018 Christian Werner https://www.androwish.org/
+Copyright (c) 2018 Rene Zaumseil [email protected]
+Copyright (c) 2020 Juliette Monsel
+Copyright (c) 2021 RedFantom <[email protected]>
+```