Make time units clear for retry configuration

[Tyler-Murphy]

No units are specified for the retryDelay option, which makes it hard to be sure what the value represents.

    // The amount of time to initially delay the retry.  Defaults to 100.
    retryDelay?: number;

I was using the option in a library that uses gaxios as a dependency of a dependency, so I had to dig through multiple layers to end up in the source code here to confirm that it uses milliseconds.

It'd be helpful for the units of the number to be in the option name, so that it's called something like retryDelayMilliseconds. Or even better, initialRetryDelayMilliseconds.

I didn't look through all other options to see whether they're missing units, but generally, I think it's helpful for all units to be specified wherever possible, to reduce ambiguity.

[JustinBeckwith]

That's a really great call, and thank you for the issue! Kind of a good news / bad news update here. Turns out - we were never actually using the retryDelay property (#143)

Instead of trying to nuance this in with the exponential backoff in place, we decided to remove the option all together in #203.

[Tyler-Murphy]

Oh no! Well, thanks for the update.

Are retries happening even though the retryDelay option wasn't doing anything? It sounds like they are, but I'd like to confirm it.

[JustinBeckwith]

Oh yeah, of course. It's just that the backoff strategy I'm place appears to work pretty well, and I didn't want to mess with it.