update README

README.md

-# PyThia Logo
+![PyThia full Logo](logo/logo_full_transparent.png)
+
+# PyThia Logo Repository
+
+Please use the standard logo (`logo/`) if possible.
+Always use the logo in a proper fashion:
+  - Make sure the logo does not overlap with other logos/text.
+  - Do not make the logo too small to be seen clearly.
+  - Check that the logo has a clear contrast to the background.
+
+Never distort or change the icon, font or colors of any of the logos.
+
+# Logo Overview
+
+| Description | transparent | white |
+| ----------- | ---- | --- |
+| logo         | <img src="logo/logo_transparent.png" height="150"/> | <img src="logo/logo_white.png" height="150"/> |
+| logo inverse | <img src="logo_inverse/logo_inverse_transparent.png" height="150"/> | <img src="logo_inverse/logo_inverse_white.png" height="150"/> |
+| logo full         | <img src="logo/logo_full_transparent.png" height="75"/> | <img src="logo/logo_full_white.png" height="75"/> |
+| logo inverse full | <img src="logo_inverse/logo_inverse_full_transparent.png" height="75"/> | <img src="logo_inverse/logo_inverse_full_white.png" height="75"/> |