Approval types (#2111)

* start approval types

* doc

* finish basic types

* add debug and codec impls to approval types

* grumbles

* remove unused AssignmentId

* remove aux-schema file

polkadot/roadmap/implementers-guide/src/types/approval.md

@@ -98,40 +98,4 @@ struct CheckedAssignmentCert {
 
 ```rust
 type DelayTranche = u32;
-```
-
-## RelayVRFStory
-
-Assignment criteria are based off of possible stories about the relay-chain block that included the candidate. More information on stories is available in [the informational page on approvals.](../protocol-approval.md#stories).
-
-```rust
-/// A story based on the VRF that authorized the relay-chain block where the candidate was
-/// included.
-///
-/// VRF Context is "A&V RC-VRF"
-struct RelayVRFStory(VRFInOut);
-```
-
-## RelayEquivocationStory
-
-```rust
-/// A story based on the candidate hash itself. Should be used when a candidate is an
-/// equivocation: when there are two relay-chain blocks with the same RelayVRFStory, but only
-/// one contains the candidate.
-///
-/// VRF Context is "A&V RC-EQUIV"
-struct RelayEquivocationStory(Hash);
-```
-
-## ExecutionTimePair
-
-```rust
-struct ExecutionTimePair {
-    // The absolute time in milliseconds that the validator claims to have taken
-    // with the block.
-    absolute: u32,
-    // The validator's believed ratio in execution time to the average, expressed as a fixed-point
-    // 16-bit unsigned integer with 8 bits before and after the point.
-    ratio: FixedU16,
-}
 ```