Merge bitcoin/bitcoin#23702: doc: Add missing optional to getblockfrompeer

aaaa34e34d doc: Add missing optional to getblockfrompeer (MarcoFalke)

Pull request description:

  Can be reviewed with `--word-diff-regex=. --ignore-all-space`

ACKs for top commit:
  Sjors:
    utACK aaaa34e34d

Tree-SHA512: 7f46c82a46b8cc19f7eb549b9aa13be8cd6849a8ef8a2ddda6d1eee6978d099fccadd29a2bf817f44d601b905f5d5f6b5d8f4f54be5ee8b914b520359c058e68

src/rpc/blockchain.cpp

@@ -777,7 +777,8 @@ static RPCHelpMan getmempoolentry()
 
 static RPCHelpMan getblockfrompeer()
 {
-    return RPCHelpMan{"getblockfrompeer",
+    return RPCHelpMan{
+        "getblockfrompeer",
         "\nAttempt to fetch block from a given peer.\n"
         "\nWe must have the header for this block, e.g. using submitheader.\n"
         "\nReturns {} if a block-request was successfully scheduled\n",
@@ -787,7 +788,7 @@ static RPCHelpMan getblockfrompeer()
         },
         RPCResult{RPCResult::Type::OBJ, "", "",
         {
-                    {RPCResult::Type::STR, "warnings", "any warnings"}
+            {RPCResult::Type::STR, "warnings", /*optional=*/true, "any warnings"},
         }},
         RPCExamples{
             HelpExampleCli("getblockfrompeer", "\"00000000c937983704a73af28acdec37b049d214adbda81d7e2a3dd146f6ed09\" 0")