doc: move memory domain docs under user mode

Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
diff --git a/doc/kernel/other/other.rst b/doc/kernel/other/other.rst
index 79f50bf..8bb3e43 100644
--- a/doc/kernel/other/other.rst
+++ b/doc/kernel/other/other.rst
@@ -15,4 +15,3 @@
    float.rst
    cxx_support.rst
    cpu_idle.rst
-   memory_domain.rst
diff --git a/doc/kernel/other/memory_domain.rst b/doc/kernel/usermode/memory_domain.rst
similarity index 100%
rename from doc/kernel/other/memory_domain.rst
rename to doc/kernel/usermode/memory_domain.rst
diff --git a/doc/kernel/usermode/usermode.rst b/doc/kernel/usermode/usermode.rst
index 381f0d7..75d84c3 100644
--- a/doc/kernel/usermode/usermode.rst
+++ b/doc/kernel/usermode/usermode.rst
@@ -11,3 +11,4 @@
 
     kernelobjects.rst
     syscalls.rst
+    memory_domain.rst