docs: sysctl: add documentation for crypto and debug

docs: sysctl: add documentation for crypto and debug

Add documentation for the /proc/sys/crypto and /proc/sys/debug
directories in the admin-guide. This includes tunables for FIPS
mode (fips_enabled, fips_name, fips_version), exception-trace,
and kprobes-optimization.

The documentation is based on source code analysis and addresses
stylistic feedback to keep it direct and concise.

Tested-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Shubham Chakraborty <chakrabortyshubham66@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Message-ID: <20260223203724.20874-1-chakrabortyshubham66@gmail.com>