Allow configuration of config reload duration

[g-hodgson-tup]

Summary

Adds a configuration option to set the duration between checks for config changes, when reloading configuration on the fly.

Example config: configReloadCheckDuration: 10s

Checklist

• Tested and/or added tests to validate that the changes work as intended, if applicable.
• Updated documentation in README.md, if applicable.

[TwiN]

What's the use case for this? I'm a big fan of keeping the configuration as simple as possible, and personally, I find this isn't particularly useful, unless there's a good reason why you need this should be configurable

[g-hodgson-tup]

Hi - in some cases we would rather reload the config in gatus faster - rather than waiting 30s for the config polling to occur.