Add current working directory to the default (although commented out) sh(1)

prompt, so it looks just like the tcsh(1) one when you uncomment it.

Reviewed by:	jilles
MFC after:	2 weeks
Sponsored by:	DARPA, AFRL
Differential Revision:	https://reviews.freebsd.org/D18673

share/skel/dot.shrc

@@ -32,8 +32,8 @@ alias g='egrep -i'
 # alias rm='rm -i'
 
 
-# # set prompt: ``username@hostname$ '' 
-# PS1="`whoami`@\h\\$ "
+# # set prompt: ``username@hostname:directory $ '' 
+# PS1="`whoami`@\h:\w \\$ "
 
 # search path for cd(1)
 # CDPATH=:$HOME