Clarify default section in config.pod

This is a minor update which hopefully makes these particular lines
read a little easier.
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/5938)

doc/man5/config.pod

@@ -18,7 +18,7 @@ started or end of file is reached. A section name can consist of
 alphanumeric characters and underscores.
 
 The first section of a configuration file is special and is referred
-to as the B<default> section this is usually unnamed and is from the
+to as the B<default> section. This section is usually unnamed and spans from the
 start of file until the first named section. When a name is being looked up
 it is first looked up in a named section (if any) and then the
 default section.