docs: security: trusted-encrypted.rst: fix code-block tag

The code-block tag is at the wrong place, causing those
warnings:

    Documentation/security/keys/trusted-encrypted.rst:112: WARNING: Literal block expected; none found.
    Documentation/security/keys/trusted-encrypted.rst:121: WARNING: Unexpected indentation.
    Documentation/security/keys/trusted-encrypted.rst:122: WARNING: Block quote ends without a blank line; unexpected unindent.
    Documentation/security/keys/trusted-encrypted.rst:123: WARNING: Block quote ends without a blank line; unexpected unindent.
Signed-off-by: NMauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: NJames Morris <jamorris@linux.microsoft.com>
Acked-by: NJarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: NJonathan Corbet <corbet@lwn.net>

Documentation/security/keys/trusted-encrypted.rst

@@ -107,12 +107,14 @@ Where::
 
 Examples of trusted and encrypted key usage:
 
-Create and save a trusted key named "kmk" of length 32 bytes::
+Create and save a trusted key named "kmk" of length 32 bytes.
 
 Note: When using a TPM 2.0 with a persistent key with handle 0x81000001,
 append 'keyhandle=0x81000001' to statements between quotes, such as
 "new 32 keyhandle=0x81000001".
 
+::
+
     $ keyctl add trusted kmk "new 32" @u
     440502848