gpgv: refresh page and add example (#19259)

* gpgv: refresh page and add example

Author: FazleArefin

pages/common/gpgv.md

@@ -1,16 +1,22 @@
 # gpgv
 
 > Verify OpenPGP signatures.
+> Note: `gpgv` reads trusted pubkeys from `~/.gnupg/trustedkeys.kbx` in absence of the `--keyring` option.
+> See also: `gpg`.
 > More information: <https://www.gnupg.org/documentation/manuals/gnupg/gpgv.html>.
 
-- Verify a signed file:
+- Verify a clearsigned or inline-signed file (the signature is embedded in the file itself):
 
-`gpgv {{path/to/file}}`
+`gpgv {{path/to/file.asc}}`
 
-- Verify a signed file using a detached signature:
+- Verify a detached signature (`.asc` or `.sig`) against its corresponding data file:
 
-`gpgv {{path/to/signature}} {{path/to/file}}`
+`gpgv {{path/to/signature.asc}} {{path/to/data_file}}`
 
-- Add a file to the list of keyrings (a single exported key also counts as a keyring):
+- Verify a detached signature using a specific public keyring or exported public key file (`.gpg` or `.kbx`):
 
-`gpgv --keyring {{./alice.keyring}} {{path/to/signature}} {{path/to/file}}`
+`gpgv --keyring {{path/to/pubkey_or_keyring.gpg}} {{path/to/signature.asc}} {{path/to/data_file}}`
+
+- Verify a detached signature using a specific public key file in plain text format (`.txt`):
+
+`gpg --dearmor {{[-o|--output]}} {{path/to/pubkey.gpg}} {{path/to/pubkey.txt}} && gpgv --keyring {{path/to/pubkey.gpg}} {{path/to/signature.asc}} {{path/to/data_file}}`