docs: trace: Fix typo in ftrace.rst

There is a typo in the sentence "A kernel developer must be
conscience ...". The word conscience should be conscious.
This patch fixes it.

Signed-off-by: Lin Yu Chen <starpt.official@gmail.com>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Link: https://lore.kernel.org/r/20230412183739.89894-1-starpt.official@gmail.com


Signed-off-by: Jonathan Corbet <corbet@lwn.net>