docs: move DPE option to experimental section

Since DPE support is experimental, move the build option for
the DPE to the experimental section.

Signed-off-by: Manish V Badarkhe <Manish.Badarkhe@arm.com>
Change-Id: I2e18947d37c52a0151b5ac656098dbae51254956
diff --git a/docs/getting_started/build-options.rst b/docs/getting_started/build-options.rst
index 6ab95f9..2f2116f 100644
--- a/docs/getting_started/build-options.rst
+++ b/docs/getting_started/build-options.rst
@@ -701,13 +701,6 @@
 
    This option defaults to 0.
 
--  ``DICE_PROTECTION_ENVIRONMENT``: Boolean flag to specify the measured boot
-   backend when ``MEASURED_BOOT`` is enabled. The default value is ``0``. When
-   set to ``1`` then measurements and additional metadata collected during the
-   measured boot process are sent to the DICE Protection Environment for storage
-   and processing. A certificate chain, which represents the boot state of the
-   device, can be queried from the DPE.
-
 -  ``MARCH_DIRECTIVE``: used to pass a -march option from the platform build
    options to the compiler. An example usage:
 
@@ -1257,6 +1250,13 @@
 Common build options
 ~~~~~~~~~~~~~~~~~~~~
 
+-  ``DICE_PROTECTION_ENVIRONMENT``: Boolean flag to specify the measured boot
+   backend when ``MEASURED_BOOT`` is enabled. The default value is ``0``. When
+   set to ``1`` then measurements and additional metadata collected during the
+   measured boot process are sent to the DICE Protection Environment for storage
+   and processing. A certificate chain, which represents the boot state of the
+   device, can be queried from the DPE.
+
 -  ``DRTM_SUPPORT``: Boolean flag to enable support for Dynamic Root of Trust
    for Measurement (DRTM). This feature has trust dependency on BL31 for taking
    the measurements and recording them as per `PSA DRTM specification`_. For