Update CORTX-MOTR-ARCHITECTURE.md (#1563)

Fix the link to parity declustered design document.

Signed-off-by: John Bent <[email protected]>

Author: johnbent

doc/CORTX-MOTR-ARCHITECTURE.md

@@ -75,7 +75,7 @@
 # Object Layout #
 +  Object is an array of blocks. Arbitrary scatter-gather IO with overwrite. Object has layout.
 +  Default layout is parity de-clustered network raid: N+K+S striping.
-   + More details about [parity declustering](doc/pdclust/index.rst)
+   + More details about [parity declustering](pdclust/index.rst)
 +  Layout takes hardware topology into account: distribute units to support fault-tolerance.  
 
 ![image](./Images/6_Object_Layout.png)