wrote descriptions and refactored for new module response with information

backend/service/events/courseService.go

@@ -1,12 +1,10 @@
 package events
 
 import (
-	"github.com/labstack/echo/v5"
 	"github.com/pocketbase/pocketbase"
 	"htwkalender/service/db"
 )
 
-func GetAllCourses(app *pocketbase.PocketBase, c echo.Context) error {
-	courses := db.GetAllCourses(app)
-	return c.JSON(200, courses)
+func GetAllCourses(app *pocketbase.PocketBase) []string {
+	return db.GetAllCourses(app)
 }