Fix two typos in comments

Note by snicolet: I use this non-functional change patch
as a pretext to correct the wrong bench number I introduced
in the message of the previous commit.

Bench: 4059356

src/endgame.cpp

@@ -216,7 +216,7 @@ Value Endgame<KRKP>::operator()(const Position& pos) const {
 }
 
 
-/// KR vs KB. This is very simple, and always returns drawish scores.  The
+/// KR vs KB. This is very simple, and always returns drawish scores. The
 /// score is slightly bigger when the defending king is close to the edge.
 template<>
 Value Endgame<KRKB>::operator()(const Position& pos) const {