Update a few outdated wrong comments

closes https://github.com/official-stockfish/Stockfish/pull/6525

No functional change

src/search.cpp

@@ -726,7 +726,7 @@ Value Search::Worker::search(
     ss->ttPv     = excludedMove ? ss->ttPv : PvNode || (ttHit && ttData.is_pv);
     ttCapture    = ttData.move && pos.capture_stage(ttData.move);
 
-    // Step 6. Static evaluation of the position
+    // Step 5. Static evaluation of the position
     Value      unadjustedStaticEval = VALUE_NONE;
     const auto correctionValue      = correction_value(*this, pos, ss);
     // Skip early pruning when in check
@@ -816,7 +816,7 @@ Value Search::Worker::search(
         }
     }
 
-    // Step 5. Tablebases probe
+    // Step 6. Tablebases probe
     if (!rootNode && !excludedMove && tbConfig.cardinality)
     {
         int piecesCount = pos.count<ALL_PIECES>();
@@ -1067,7 +1067,7 @@ moves_loop:  // When in check, search starts here
         // Depth conditions are important for mate finding.
         if (!rootNode && pos.non_pawn_material(us) && !is_loss(bestValue))
         {
-            // Skip quiet moves if movecount exceeds our FutilityMoveCount threshold
+            // Skip quiet moves if movecount exceeds our threshold
             if (moveCount >= (3 + depth * depth) / (2 - improving))
                 mp.skip_quiet_moves();
 
@@ -1885,8 +1885,8 @@ void update_all_stats(const Position& pos,
 }
 
 
-// Updates histories of the move pairs formed by moves
-// at ply -1, -2, -3, -4, and -6 with current move.
+// Updates the continuation histories for the move pairs formed by
+// the current move and the moves played in previous plies.
 void update_continuation_histories(Stack* ss, Piece pc, Square to, int bonus) {
     static constexpr std::array<ConthistBonus, 6> conthist_bonuses = {
       {{1, 1071}, {2, 753}, {3, 329}, {4, 539}, {5, 124}, {6, 434}}};