docs: rpc help correction (dashpay#5877)

## Issue being fixed or feature implemented
Help field showed wrong type

## What was done?
Changed height to number instead of string


## How Has This Been Tested?
Locally

## Breaking Changes
N/A

## Checklist:
_Go over all the following points, and put an `x` in all the boxes that
apply._
- [x] I have performed a self-review of my own code
- [ ] I have commented my code, particularly in hard-to-understand areas
- [ ] I have added or updated relevant unit/integration/functional/e2e
tests
- [ ] I have made corresponding changes to the documentation
- [x] I have assigned this pull request to a milestone _(for repository
code-owners and collaborators only)_

Author: thephez

src/rpc/blockchain.cpp

@@ -1165,7 +1165,7 @@ static UniValue getblock(const JSONRPCRequest& request)
                                 {RPCResult::Type::OBJ, "cbTx", "The coinbase special transaction",
                                     {
                                         {RPCResult::Type::NUM, "version", "The coinbase special transaction version"},
-                                        {RPCResult::Type::STR_HEX, "height", "The block height"},
+                                        {RPCResult::Type::NUM, "height", "The block height"},
                                         {RPCResult::Type::STR_HEX, "merkleRootMNList", "The merkle root of the masternode list"},
                                         {RPCResult::Type::STR_HEX, "merkleRootQuorums", "The merkle root of the quorum list"},
                                     }},