file-log Plugin Document improvement

### Where is the problem?

https://docs.konghq.com/hub/kong-inc/file-log/

### What happened?

**Below are the points can be improved :**

- Latencies in the file log plugin doesn't show any time format whether it is in milliseconds/seconds .
- proxy is the time it took for the final service to process the request.

The above sentence can be improved grammatically.

### What did you expect to happen?

**Below are my expectation :**

### - Latencies should contain the time format :

latencies contains some data about the latencies involved:
proxy is the time it took for the final service to process the request in milliseconds.
kong is the internal Kong latency that it took to run all the plugins in milliseconds.
request is the time elapsed between the first bytes were read from the client and after the last bytes were sent to the
client in milliseconds.

### - Small correction
Original Sentence : proxy is the time it took for the final service to process the request.
My Expectation : proxy is the time taken by the final service to process the request.

### Code of Conduct and Community Expectations

- [X] I agree to follow this project's Code of Conduct
- [X] I agree to abide by the Community Expectations

Start with the file-log plugin page at https://docs.konghq.com/hub/kong-inc/file-log/ and inspect the latencies descriptions. Confirm the proxy, kong, and request values are identified as milliseconds and that the proxy sentence is grammatically improved; check the repository notice before making changes because this repository is archived and points to a replacement.

Written by the indexing model from the issue text.