update forum background color + documentation

themes/Explanations.md

@@ -12,6 +12,10 @@
 - `PRIMARY_660` : Background button aside of chatbox
 - `PRIMARY_700` : Background of chatbox
 - `PRIMARY_800` : Backgroud of menubar and in profile
+- `PRIMARY_560` : Background of card in forums
+
+> [Some utils](https://github.com/nexpid/VendettaThemeUtil) and
+> [some documentation](https://docs.riichi.tech/objects/semantic-colors)
 
 # [Themes+](https://vendetta.nexpid.xyz/themes-plus)
 

themes/VendettaOLED.json

@@ -15,6 +15,7 @@
     "SPOILER_REVEALED_BACKGROUND": ["#232428"]
   },
   "rawColors": {
+    "PRIMARY_560": "#08080A",
     "PRIMARY_600": "#000000",
     "PRIMARY_630": "#000000",
     "PRIMARY_660": "#08080A",