[FOLD] Review feedback from @thejohnfreeman and @scottschurr:

* Use std::if_any to simplify the JobQueue::isOverloaded loop.
* Improved and clarified a couple of different comments in the TxQ.

src/ripple/app/misc/TxQ.h

@@ -613,14 +613,25 @@ class TxQ
         }
     };
 
-    /// Used for sorting @ref MaybeTx by `feeLevel` descending, then by
-    /// transaction ID ascending
+    /// Used for sorting @ref MaybeTx
     class OrderCandidates
     {
     public:
         /// Default constructor
         explicit OrderCandidates() = default;
 
+        /** Sort @ref MaybeTx by `feeLevel` descending, then by
+         * transaction ID ascending
+         *
+         * The transaction queue is ordered such that transactions
+         * paying a higher fee are in front of transactions paying
+         * a lower fee, giving them an opportunity to be processed into
+         * the open ledger first. Within transactions paying the same
+         * fee, order by the arbitrary but consistent transaction ID.
+         * This allows validators to build similar queues in the same
+         * order, and thus have more similar initial proposals.
+         *
+         */
         bool
         operator()(const MaybeTx& lhs, const MaybeTx& rhs) const
         {

src/ripple/app/misc/impl/TxQ.cpp

@@ -1214,6 +1214,12 @@ TxQ::apply(
         }
         if (lastRIter == byFee_.rend())
         {
+            // The only way this condition can happen is if the entire
+            // queue is filled with transactions from this account. This
+            // is impossible with default settings - minimum queue size
+            // is 2000, and an account can only have 10 transactions
+            // queued. However, it can occur if settings are changed,
+            // and there is unit test coverage.
             JLOG(j_.info())
                 << "Queue is full, and transaction " << transactionID
                 << " would kick a transaction from the same account ("

src/ripple/core/impl/JobQueue.cpp

@@ -168,13 +168,9 @@ JobQueue::addLoadEvents(JobType t, int count, std::chrono::milliseconds elapsed)
 bool
 JobQueue::isOverloaded()
 {
-    for (auto& x : m_jobData)
-    {
-        if (x.second.load().isOver())
-            return true;
-    }
-
-    return false;
+    return std::any_of(m_jobData.begin(), m_jobData.end(), [](auto& entry) {
+        return entry.second.load().isOver();
+    });
 }
 
 Json::Value