doc: Fix comment syntax error

Author: willcl-ark

src/kernel/mempool_options.h

@@ -18,7 +18,7 @@ class CBlockPolicyEstimator;
 
 /** Default for -maxmempool, maximum megabytes of mempool memory usage */
 static constexpr unsigned int DEFAULT_MAX_MEMPOOL_SIZE_MB{300};
-//** Default for -maxmempool when blocksonly is set */
+/** Default for -maxmempool when blocksonly is set */
 static constexpr unsigned int DEFAULT_BLOCKSONLY_MAX_MEMPOOL_SIZE_MB{5};
 /** Default for -mempoolexpiry, expiration time for mempool transactions in hours */
 static constexpr unsigned int DEFAULT_MEMPOOL_EXPIRY_HOURS{336};