Update 'pkcs11-tools.md'

pkcs11-tools.md

@@ -34,16 +34,31 @@ List certificates:
 $ pkcs11-tool --list-objects --type cert
 ```
 
+Read certificate:
+```shell
+$ pkcs11-tool --read-object --id $CERT_ID --type cert --output-file cert.der
+```
+
 List public keys:
 ```shell
 $ pkcs11-tool --list-objects --type pubkey
 ```
 
+Read public key:
+```shell
+$ pkcs11-tool --read-object --id $CERT_ID --type pubkey --output-file pubkey.der
+```
+
 List private keys:
 ```shell
 $ pkcs11-tool --login --list-objects --type privkey
 ```
 
+Sign a file:
+```shell
+$ pkcs11-tool --id 02 -s -m ECDSA --input-file FILE --output-file FILE.sig
+```
+
 
 # `p11tool`