Emphasize that specifying the keyword only will result in the defaults
for each option to be used.
Issue: 7853
Format::
from_base64: [[bytes <value>] [, offset <offset_value> [, mode: strict|rfc4648|rfc2045]]]
+ from_base64
There are defaults for each of the options:
- ``bytes`` defaults to the length of the input buffer
- ``offset`` defaults to ``0`` and must be less than ``65536``
- ``mode`` defaults to ``rfc4648``
+The second example shows the rule keyword only which will cause the default values for each option to
+be used.
+
Note that both ``bytes`` and ``offset`` may be variables from `byte_extract` and/or `byte_math` in
later versions of Suricata. They are not supported yet.