runtime(doc): remove E1520 tag (#13289)

Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/doc/builtin.txt b/runtime/doc/builtin.txt
index a4eb95e..029c08b 100644
--- a/runtime/doc/builtin.txt
+++ b/runtime/doc/builtin.txt
@@ -6690,8 +6690,6 @@
 		precision, the argument(s) to be used must also be specified
 		using a {n$} positional argument specifier. See |printf-$|.
 
-
-							*E1520*
 		The conversion specifiers and their meanings are:
 
 				*printf-d* *printf-b* *printf-B* *printf-o*
@@ -6885,11 +6883,11 @@
 			%1$d at width %2$d is: %01$*2$.3$d
 
 							*E1507*
-		This internal error indicates that the logic to
-		parse a positional format error ran into a problem
-		that couldn't be otherwise reported. Please file a
-		bug against vim if you run into this, copying the
-		exact format string and parameters that were used.
+		This internal error indicates that the logic to parse a
+		positional format argument ran into a problem that couldn't be
+		otherwise reported.  Please file a bug against Vim if you run
+		into this, copying the exact format string and parameters that
+		were used.
 
 
 prompt_getprompt({buf})					*prompt_getprompt()*