confusing suggestion if `include.only` argument of `library` was used.

That's probably not so common but got me scratching my head.

```
library(data.table, include.only = c("setDT"))
library(fcuk)
data.table
# Error: object 'data.table' not found
# Did you mean : data.table or as.data.table ?
```

`data.table` not found, try `data.table` ? :)