Update MD013/line-length default mode to prevent trailing non-whitespace text that begins *just over* the length limit (edge case).

test/long-lines-thresholds.md

@@ -13,7 +13,7 @@ Text text text text text text text textx text
 
 Text text text text text text text textxe text
 
-{MD013:-2} {MD013:-4}
+{MD013:-2} {MD013:-4} {MD013:-6}
 
 ## Text text text text text te text
 
@@ -25,7 +25,7 @@ Text text text text text text text textxe text
 
 ## Text text text text text textxe text
 
-{MD013:-2} {MD013:-4}
+{MD013:-2} {MD013:-4} {MD013:-6}
 
 ```text
 Text text text te text
@@ -35,7 +35,7 @@ Text text text textx text
 Text text text textxe text
 ```
 
-{MD013:-3} {MD013:-4}
+{MD013:-3} {MD013:-4} {MD013:-5}
 
     Text text tex text
     Text text text text
@@ -43,7 +43,7 @@ Text text text textxe text
     Text text textxe text
     Text text textxet text
 
-{MD013:-2} {MD013:-3}
+{MD013:-2} {MD013:-3} {MD013:-4}
 
 <!-- markdownlint-configure-file {
   "code-block-style": false,