doc: spelling fixes

src/test/coins_tests.cpp

@@ -275,7 +275,7 @@ UtxoData::iterator FindRandomFrom(const std::set<COutPoint> &utxoSet) {
 // except the emphasis is on testing the functionality of UpdateCoins
 // random txs are created and UpdateCoins is used to update the cache stack
 // In particular it is tested that spending a duplicate coinbase tx
-// has the expected effect (the other duplicate is overwitten at all cache levels)
+// has the expected effect (the other duplicate is overwritten at all cache levels)
 BOOST_AUTO_TEST_CASE(updatecoins_simulation_test)
 {
     bool spent_a_duplicate_coinbase = false;