p2p/message: Changed evidence message to contain evidence, not a list… (#394)

* p2p/message: Changed evidence message to contain evidence, not a list of evidence

* Update spec/p2p/messages/evidence.md

Co-authored-by: Callum Waters <cmwaters19@gmail.com>

Co-authored-by: Callum Waters <cmwaters19@gmail.com>

spec/p2p/messages/evidence.md

@@ -14,10 +14,10 @@ Evidence has one channel. The channel identifier is listed below.
 
 ## Message Types
 
-### EvidenceList
+### Evidence
 
-EvidenceList consists of a list of verified evidence. This evidence will already have been propagated throughout the network. EvidenceList is used in two places, as a p2p message and within the block [block](../../core/data_structures.md#block) as well.
+Verified evidence that has already been propagated throughout the network. This evidence will appear within the EvidenceList struct of a [block](../../core/data_structures.md#block) as well.
 
 | Name     | Type                                                        | Description            | Field Number |
 |----------|-------------------------------------------------------------|------------------------|--------------|
-| evidence | repeated [Evidence](../../core/data_structures.md#evidence) | List of valid evidence | 1            |
+| evidence | [Evidence](../../core/data_structures.md#evidence) | Valid evidence | 1            |