doc: fix mismatched ACRN version
Document was updated to use v2.1 but left a references to v1.6
@@ -136,7 +136,7 @@ Update ACRN hypervisor image
Refer to :ref:`getting-started-building` to set up the ACRN build
environment on your development workstation.
- Clone the ACRN source code and check out to the tag v1.6:
+ Clone the ACRN source code and check out to the tag v2.1:
.. code-block:: none
