docs: Added Kerberos V5 to the --user SSPI current credentials usage

docs/curl.1

@@ -1627,16 +1627,17 @@ The user name and passwords are split up on the first colon, which makes it
 impossible to use a colon in the user name with this option. The password can,
 still.
 
-If you use a Windows SSPI-enabled curl binary and perform either Negotiate or
-NTLM authentication then you can force curl to select the user name and password
-from your environment by specifying a single colon with this option: "-u :".
+If you use a Windows SSPI-enabled curl binary and perform Kerberos V5,
+Negotiate or NTLM authentication then you can tell curl to select the user
+name and password from your environment by specifying a single colon with this
+option: "-u :".
 
 If this option is used several times, the last one will be used.
 .IP "-U, --proxy-user <user:password>"
 Specify the user name and password to use for proxy authentication.
 
 If you use a Windows SSPI-enabled curl binary and do either Negotiate or NTLM
-authentication then you can force curl to select the user name and password
+authentication then you can tell curl to select the user name and password
 from your environment by specifying a single colon with this option: "-U :".
 
 If this option is used several times, the last one will be used.