fix last edit dates

Author: Frotty

_doc/manual.md

@@ -1,7 +1,7 @@
 ---
 title: Manual
 excerpt: Formal description of all language features.
-date: 2019-04-04
+date: 2023-05-01
 icon:
   name: icon_info
 color: blue

_doc/showcase.md

@@ -1,7 +1,7 @@
 ---
 title: Showcase
 excerpt: Maps and Libraries achieved with WurstScript.
-date: 2021-11-21
+date: 2022-01-21
 icon:
   name: icon_genius
 color: primary

_doc/tutorials.md

@@ -1,7 +1,7 @@
 ---
 title: Tutorials
 excerpt: Wurst guides on specific topics for aspiring developers.
-date: 2017-07-26
+date: 2021-12-04
 icon:
   name: icon_lifesaver
 color: purple