add parameters example for eth rpc

apps/block_scout_web/lib/block_scout_web/controllers/api/rpc/eth_controller.ex

@@ -12,12 +12,18 @@ defmodule BlockScoutWeb.API.RPC.EthController do
       notes: """
       the `earliest` parameter will not work as expected currently, because genesis block balances
       are not currently imported
+      """,
+      example: """
+      {"id": 0, "jsonrpc": "2.0", "method": "eth_getBalance", "params": ["0x0000000000000000000000000000000000000007", "2"]}
       """
     },
     "eth_getLogs" => %{
       action: :eth_get_logs,
       notes: """
       Will never return more than 1000 log entries.
+      """,
+      example: """
+      {"id": 0, "jsonrpc": "2.0", "method": "eth_getLogs", "params": [{"address": "0x0000000000000000000000000000000000000026","topics": ["0x01"]}]}
       """
     }
   }

apps/block_scout_web/lib/block_scout_web/templates/api_docs/eth_rpc.html.eex

@@ -22,11 +22,13 @@
           <tr>
             <th>Supported Method</th>
             <th>Notes</th>
+            <th>Parameters example</th>
           </tr>
           <%= for {method, info} <- Map.to_list(@documentation) do %>
             <tr>
               <td> <a href="https://github.com/ethereum/wiki/wiki/JSON-RPC#<%= method %>"> <%= method %> </a> </td>
               <td> <%= Map.get(info, :notes, "N/A") %> </td>
+              <td> <%= Map.get(info, :example, "N/A") %> </td>
             </tr>
           <% end %>
         </table>