For people using autogenerated summaries, this is one of the hot spots in the memory department.
We don't need to split al the content into words to do proper summary truncation.
This is obviously more effective:
```
BenchmarkTestTruncateWordsToWholeSentence-4 300000 4720 ns/op 0 B/op 0 allocs/op
BenchmarkTestTruncateWordsToWholeSentenceOld-4 100000 17699 ns/op 3072 B/op 3 allocs/op
```