docs(sdl): document audited attributes (#924)

Signed-off-by: Artur Troian <troian.ap@gmail.com>

_docs/sdl.md

@@ -118,15 +118,23 @@ Example:
 
 #### profiles.placement
 
-`profiles.placement` is map of named datacenter profiles.  Each profile specifies required datacenter attributes and pricing
+`profiles.placement` is map of named datacenter profiles. Each profile specifies required datacenter attributes and pricing
 configuration for each [compute profile](#profilescompute) that will be used within the datacenter.
+It also specifies optional list of signatures of which tenants expects audit of datacenter attributes.
 
 Example:
 
 ```yaml
 westcoast:
   attributes:
     region: us-west
+  signedBy: # optional, allOf has higher priority, anyOf is ignored if there is at least one key in allOf
+    allOf: # array of keys tenant expects attributes to be validated by. if all but one validated, provider cannot bid
+      - signer1
+      - signer2
+    anyOf: # array of keys tenant expects attributes to be validated by. provider can bid if one of keys has put signature 
+      - signer3
+      - signer4
   pricing:
     web:
       denom: uakt