Added explanation

Author: Soupstraw

message-index/messages/GHC-21231/escape-seq-oor/index.md

@@ -0,0 +1,17 @@
+---
+title: "Typo: lower-case class name"
+---
+
+## Error Message
+
+```
+EscapeSeqOutOfRange.hs:4:13: error:
+    numeric escape sequence out of range at character '2'
+  |
+4 | x = '\1114112'
+  |             ^
+```
+## Explanation
+
+This example shows that a numeric escape sequence with a value higher than 
+`1114111` throws an error, but numbers lower than that don't.