changed detach sig verification commandline (-a => -f <file>)

man/pcp1.pod

@@ -103,11 +103,11 @@ Pretty Curved Privacy - File encryption using eliptic curve cryptography.
                             the file specified with -I (or stdin).
                             The public key required for this must
                             exist in your vault file.
-  -a --detach               Write a detached signature file, which doesn't
+  -f --sigfile <file>       Write a detached signature file, which doesn't
                             contain the original content. Output will be
                             z85 encoded always. To verify, you need to
                             specify the original file to be verified
-                            against using -I as well (plus -a).
+                            against using -I as well (plus -f <sigfile>).
   
   Encoding Options:
   -z --z85-encode           Encode something to Z85 encoding. Use
@@ -303,7 +303,11 @@ be Z85 encoded.
 
 Example:
 
- pcp1 -g -I message.txt -O message.asc -g --detach
+ pcp1 -g -I message.txt -O -g --sigfile message.sig
+
+Verification by recipient:
+
+ pcp -c -f message.sig -I message.txt
 
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