docs: alienware-wmi: fix typo

Fix a typo in the manual fan control description ("aproximate" ->
"approximate").

Signed-off-by: Akiyoshi Kurita <[e-mail]>
Reviewed-by: Bagas Sanjaya <[e-mail]>
Reviewed-by: Kurt Borja <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Ilpo Järvinen <[e-mail]>

Documentation/admin-guide/laptops/alienware-wmi.rst

···
 
 Manual fan control on the other hand, is not exposed directly by the AWCC
 interface. Instead it let's us control a fan `boost` value. This `boost` value
-has the following aproximate behavior over the fan pwm:
+has the following approximate behavior over the fan pwm:
 
 ::