go-md2man.1.md: more formatting

1. Use some standard formatting rules, such as
 - literals are bold;
 - variables are italic;
 - file names are italic (even when literal);
 - use ``` for code blocks.

2. Add an example with shell redirection.

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>

go-md2man.1.md

@@ -5,18 +5,24 @@ go-md2man 1 "January 2015" go-md2man "User Manual"
 go-md2man - Convert markdown files into manpages
 
 # SYNOPSIS
-go-md2man -in=[/path/to/md/file] -out=[/path/to/output]
+**go-md2man** [**-in**=*/path/to/md/file*] [**-out**=*/path/to/output*]
 
 # DESCRIPTION
-go-md2man converts standard markdown formatted documents into manpages. It is
+**go-md2man** converts standard markdown formatted documents into manpages. It is
 written purely in Go so as to reduce dependencies on 3rd party libs.
 
 By default, the input is stdin and the output is stdout.
 
 # EXAMPLES
-Convert the markdown file "go-md2man.1.md" into a manpage:
+Convert the markdown file *go-md2man.1.md* into a manpage:
+```
+go-md2man < go-md2man.1.md > go-md2man.1
+```
 
+Same, but using command line arguments instead of shell redirection:
+```
 go-md2man -in=go-md2man.1.md -out=go-md2man.1
+```
 
 # HISTORY
-January 2015, Originally compiled by Brian Goff( cpuguy83@gmail.com )
+January 2015, Originally compiled by Brian Goff (cpuguy83@gmail.com).