fix(el3-spmc): remove experimental flag

The EL3 SPMC is known to be deployed into end products and properly
tested since its introduction into TF-A v2.7.

Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
Change-Id: I96bb897cfefef20c33cfc39627b10746dce5485c
diff --git a/docs/getting_started/build-options.rst b/docs/getting_started/build-options.rst
index 43b13d6..e54b0b9 100644
--- a/docs/getting_started/build-options.rst
+++ b/docs/getting_started/build-options.rst
@@ -898,7 +898,7 @@
    Dispatcher option (``SPD=spmd``). When enabled (1) it indicates the SPMC
    component runs at the EL3 exception level. The default value is ``0`` (
    disabled). This configuration supports pre-Armv8.4 platforms (aka not
-   implementing the ``FEAT_SEL2`` extension). This is an experimental feature.
+   implementing the ``FEAT_SEL2`` extension).
 
 -  ``SPMC_AT_EL3_SEL0_SP`` : Boolean option to enable SEL0 SP load support when
    ``SPMC_AT_EL3`` is enabled. The default value if ``0`` (disabled). This