Documentation/features/vm: pte_special now supported by ARC

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

Documentation/features/vm/pte_special/arch-support.txt

@@ -7,7 +7,7 @@
     |         arch |status|
     -----------------------
     |       alpha: | TODO |
-    |         arc: | TODO |
+    |         arc: |  ok  |
     |         arm: |  ok  |
     |       arm64: |  ok  |
     |       avr32: | TODO |