Merge #19268: doc: Add non-thread-safe note to FeeFilterRounder::round()

d842e6a doc: Add non-thread-safe note to FeeFilterRounder::round() (Hennadii Stepanov)

Pull request description:

  The `FastRandomContext` class is documented as not thread-safe.
  This PR adds a relevant note to the `FeeFilterRounder::round()` function declaration.

  Close #19254

ACKs for top commit:
  MarcoFalke:
    self ACK d842e6a
  practicalswift:
    ACK d842e6a: explicit is better than implicit
  naumenkogs:
    ACK d842e6a

Tree-SHA512: 538508f24b9cb29baece6a64108e2c5fc3960768c6475c4f2baf48a4a7bdb96dcef1a74d21a4822e1f8635e1375362986da4e3a20f5644129046a354c4b0a8a0

Author: MarcoFalke

src/policy/fees.h

@@ -273,7 +273,7 @@ class FeeFilterRounder
     /** Create new FeeFilterRounder */
     explicit FeeFilterRounder(const CFeeRate& minIncrementalFee);
 
-    /** Quantize a minimum fee for privacy purpose before broadcast **/
+    /** Quantize a minimum fee for privacy purpose before broadcast. Not thread-safe due to use of FastRandomContext */
     CAmount round(CAmount currentMinFee);
 
 private: