docs: timers: drop documentation about LB_BIAS

The LB_BIAS feature was removed in commit 1c1b8a7 ("sched/fair:
Replace source_load() & target_load() with weighted_cpuload()"), so drop
the mention that it is disabled in the no_hz case.

Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>

Link: https://lore.kernel.org/r/1595088518-28116-1-git-send-email-Julia.Lawall@inria.fr
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/timers/no_hz.rst

@@ -171,8 +171,6 @@ not come for free:
 	slightly differently than those for non-adaptive-tick CPUs.
 	This might in turn perturb load-balancing of real-time tasks.
 
-6.	The LB_BIAS scheduler feature is disabled by adaptive ticks.
-
 Although improvements are expected over time, adaptive ticks is quite
 useful for many types of real-time and compute-intensive applications.
 However, the drawbacks listed above mean that adaptive ticks should not