Fixed typo (vi leftover).

There was a trailing :w at a line, which didn't make sense in context
of the sentence/styling. Removed it, because I think it's a leftover
vi command.

CLA: trivial
Signed-off-by: NTobias Stoeckmann <tobias@stoeckmann.org>
Reviewed-by: NMatt Caswell <matt@openssl.org>
Reviewed-by: NMatthias St. Pierre <Matthias.St.Pierre@ncp-e.com>
Reviewed-by: NRichard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/7875)

(cherry picked from commit 143b631639f95822e5e00768254fa35c787f6396)

doc/man1/ca.pod

@@ -230,7 +230,7 @@ The section of the configuration file containing certificate extensions
 to be added when a certificate is issued (defaults to B<x509_extensions>
 unless the B<-extfile> option is used). If no extension section is
 present then, a V1 certificate is created. If the extension section
-is present (even if it is empty), then a V3 certificate is created. See the:w
+is present (even if it is empty), then a V3 certificate is created. See the
 L<x509v3_config(5)> manual page for details of the
 extension section format.