Add FILES section to cassh.1

Adjust a Bl -width and some Pa while there.

cassh.1

@@ -53,11 +53,11 @@ and
 files based on the active Certification Authority.
 .Pp
 A Certification Authority directory consists of a
-.Pa ca.pub
+.Pa ./ca.pub
 file corresponding to the public key of it, a
-.Pa pubkeys/
+.Pa ./pubkeys/
 directory which holds the public keys to be signed, and an optional
-.Pa serial.txt
+.Pa ./serial.txt
 file holding the current serial number for the issued certificates.
 .Pp
 The following commands are available to
@@ -79,7 +79,7 @@ and
 .Ar principals .
 The recognized tokens are:
 .Pp
-.Bl -tag -width XXXX -offset indent -compact
+.Bl -tag -width MMMM -offset indent -compact
 .It %%
 A literal
 .Sq % .
@@ -123,6 +123,15 @@ See
 .Xr sshd 8 SSH_KNOWN_HOSTS FILE FORMAT
 for details.
 .El
+.Sh FILES
+.Bl -tag -width MMMMMMMMMMMMMM -compact
+.It Pa ./ca.pub
+Certification Authority public key
+.It Pa ./pubkeys/
+Directory containing the public keys to be signed
+.It Pa ./serial.txt
+Last issued serial
+.El
 .Sh EXIT STATUS
 .Ex -std
 .Sh SEE ALSO