Fix spelling of "length".
diff --git a/relaxng.c b/relaxng.c
index f600d07..370e314 100644
--- a/relaxng.c
+++ b/relaxng.c
@@ -8347,7 +8347,7 @@
  * xmlRelaxNGValidatePushCData:
  * @ctxt:  the RelaxNG validation context
  * @data:  some character data read
- * @len:  the lenght of the data
+ * @len:  the length of the data
  *
  * check the CData parsed for validation in the current stack
  *