Replace characters to circumvent exercism/exercism#6225 (#2640)

Author: SleeplessByte

exercises/concept/windowing-system/.docs/instructions.md

@@ -4,26 +4,26 @@ In this exercise, you will be simulating a windowing based computer system.
 You will create some windows that can be moved and resized.
 The following image is representative of the values you will be working with below.
 
-```
+```text
                   <--------------------- screenSize.width --------------------->
 
-       ^          ╔════════════════════════════════════════════════════════════╗
-       |          ║                                                            ║
-       |          ║          position.x,_                                      ║
-       |          ║          position.y  \                                     ║
-       |          ║                       \<----- size.width ----->            ║
-       |          ║                 ^      *──────────────────────┐            ║
-       |          ║                 |      │        title         │            ║
-       |          ║                 |      ├──────────────────────┤            ║
-screenSize.height ║                 |      │                      │            ║
-       |          ║            size.height │                      │            ║
-       |          ║                 |      │       contents       │            ║
-       |          ║                 |      │                      │            ║
-       |          ║                 |      │                      │            ║
-       |          ║                 v      └──────────────────────┘            ║
-       |          ║                                                            ║
-       |          ║                                                            ║
-       v          ╚════════════════════════════════════════════════════════════╝
+       ^          ┌────────────────────────────────────────────────────────────┐
+       |          │                                                            │
+       |          │         position.x, _                                      │
+       |          │         position.y   \                                     │
+       |          │                       \<----- size.width ----->            │
+       |          │                 ^      *──────────────────────┐            │
+       |          │                 |      │        title         │            │
+       |          │                 |      ├──────────────────────┤            │
+screenSize.height │                 |      │                      │            │
+       |          │            size.height │                      │            │
+       |          │                 |      │       contents       │            │
+       |          │                 |      │                      │            │
+       |          │                 |      │                      │            │
+       |          │                 v      └──────────────────────┘            │
+       |          │                                                            │
+       |          │                                                            │
+       v          └────────────────────────────────────────────────────────────┘
 ```
 
 📣 To practice your wide range of JavaScript skills, **try to solve tasks 1 and 2 with prototype syntax and the remaining tasks with class syntax**.