docs: fix typo (#837)

README.md

@@ -849,7 +849,7 @@ BENCHMARK(BM_OpenMP)->Range(8, 8<<10)->MeasureProcessCPUTime()->UseRealTime();
 Normally, the entire duration of the work loop (`for (auto _ : state) {}`)
 is measured. But sometimes, it is necessary to do some work inside of
 that loop, every iteration, but without counting that time to the benchmark time.
-That is possible, althought it is not recommended, since it has high overhead.
+That is possible, although it is not recommended, since it has high overhead.
 
 ```c++
 static void BM_SetInsert_With_Timer_Control(benchmark::State& state) {