update NEWS number

Author: ben-schwen

NEWS.md

@@ -67,7 +67,7 @@ rowwiseDT(
 
 10. Fixed possible segfault in `setDT(df); attr(df, key) <- value; set(df, ...)`, i.e. adding columns to an object with `set()` that was converted to data.table with `setDT()` and later had attributes add with `attr<-`, [#6410](https://github.com/Rdatatable/data.table/issues/6410). Thanks to @hongyuanjia for the report and @ben-schwen for the PR. Note that `setattr()` should be preferred for adding attributes to a data.table.
 
-6. `fread()` automatically detects timestamps with sub-second accuracy again, [#6440](https://github.com/Rdatatable/data.table/issues/6440). This was a regression due to interference with new `dec='auto'` support. Thanks @kav2k for the concise report and @MichaelChirico for the fix.
+11. `fread()` automatically detects timestamps with sub-second accuracy again, [#6440](https://github.com/Rdatatable/data.table/issues/6440). This was a regression due to interference with new `dec='auto'` support. Thanks @kav2k for the concise report and @MichaelChirico for the fix.
 
 ## NOTES