message: [Docs] add short documentation for /rest/blockhashbyheight
diff: @@ -31,6 +31,11 @@ With the /notxdetails/ option JSON response will only contain the transaction ha
  Given a block hash: returns <COUNT> amount of blockheaders in upward direction.
  +#### Blockhash by height
  +`GET /rest/blockhashbyheight/<HEIGHT>.<bin|hex|json>`
  +
  +Given a height: returns hash of block in best-block-chain at height provided.
  +
  #### Chaininfos
  `GET /rest/chaininfo.json`
  