docs: document how the logo is made in docs.md

docs/src/docs.md

@@ -1,2 +1,20 @@
 # Technical documentation
 
+
+## Logo design
+
+In the spirit of Delibay and PRJS logos, a simple gradient was chosen on the project name. Like PRJS, the text is an ASCII art creation. It was generated with the help of [Calligraphy](https://calligraphy.geopjr.dev/) with the font `Blocky`. The gradient is composed of these 2 colors: `#fc1100`, `#ffb000` applied to this text piece.
+
+```
+████████  ██       ██     ██ 
+██     ██ ██        ██   ██  
+██     ██ ██         ██ ██   
+████████  ██          ███    
+██        ██         ██ ██   
+██        ██        ██   ██  
+██        ████████ ██     ██ 
+```
+
+It was colored in Inkscape with a monospace font (any monospace font should be okay) and exported in SVG:
+
+![logo of PLX](../../static/logo.svg)