mk-ca-bundle.1: mention new -f, fix outputfile output

also edited a few sentences to become more verbose

docs/mk-ca-bundle.1

-.Dd April 27, 2012
+.Dd Jan 5, 2013
 .Dt MK-CA-BUNDLE 1
 .Os
 .Sh NAME
 .Nm mk-ca-bundle
-.Nd create a new ca-bundle.crt from mozilla's certdata.txt
+.Nd convert mozilla's certdata.txt to PEM format
 .Sh SYNOPSIS
 .Nm
 .Op Fl bilnqtuv
-.Or outputfile
+[outputfile]
 .Sh DESCRIPTION
 The
 .Nm
-tool downloads the certdata.txt file from Mozilla's source tree, then
-parses certdata.txt and extracts CA Root Certificates into PEM format.
+tool downloads the certdata.txt file from Mozilla's source tree over HTTP,
+then parses certdata.txt and extracts CA Root Certificates into PEM format.
 These are then processed with the OpenSSL commandline tool to produce the
-final ca-bundle.crt file.
+final ca-bundle file.
+
+The default \fIoutputfile\fP name is \fBca-bundle.crt\fP. By setting it to '-'
+(a single dash) you will get the output sent to STDOUT instead of a file.
+
+The PEM format this scripts uses for output makes the result readily available
+for use by just about all OpenSSL or GnuTLS powered applications, such as
+curl, wget and more.
 .Sh OPTIONS
 The following options are supported by
 .Nm :
 .Bl -tag -width _h
 .It Fl b
-backup an existing version of ca-bundle.crt
+backup an existing version of \fIoutputfilename\fP.
+.It Fl f
+force rebuild even if certdata.txt is current (Added in version 1.17)
 .It Fl i
 print version info about used modules
 .It Fl l
@@ -42,9 +51,11 @@ be verbose and print out processed CAs
 .Xr curl 1
 .Sh HISTORY
 .Nm
-was based on the parse-certs script written by
+is a command line tool that is shipped as part of every curl and libcurl
+release (see http://curl.haxx.se/). It was originally based on the parse-certs
+script written by
 .An Roland Krikava
-and hacked by
+and was later much improved by
 .An Guenter Knauf .
 This manual page was written by
 .An Jan Schaumann