Update favicon
Generated a new favicon that looks a bit better. We still use a lambda character but with a green background and black foreground. The green is the same as the green used in the header lines for pages.
This icon was generated via https://favicon.io/favicon-generator/ with the following options:
- Text: lambda character
- Font Color: #000 (black)
- Background Color: #99c99 (the green from the heading line on each page)
- Font family: Noto Serif
- Font Variant: Bold 700 Normal
- Font Size: 110 (default)
Edited by Raymond Toy