patch 8.2.3914: various spelling mistakes in comments

Problem:    Various spelling mistakes in comments.
Solution:   Fix the mistakes. (Dominique Pellé, closes #9416)
diff --git a/src/misc1.c b/src/misc1.c
index ad26ab3..a8bc08e 100644
--- a/src/misc1.c
+++ b/src/misc1.c
@@ -371,7 +371,7 @@
 	return 1;
 
 #ifdef FEAT_FOLDING
-    // A folded lines is handled just like an empty line.
+    // Folded lines are handled just like an empty line.
     // NOTE: Caller must handle lines that are MAYBE folded.
     if (lineFolded(wp, lnum) == TRUE)
 	return 1;