docs: Update the FAQ (#12793)

docs/FAQ.md

@@ -1,5 +1,70 @@
 # Frequently Asked Questions
 
+## When will my PR or fix get released?
+
+Telegraf has four minor releases a year in March, June, September, and
+December. In between each of those minor releases, there are 2-4 bug fix
+releases that happen every 3 weeks.
+
+PRs that resolves issues are released in the next release. PRs that introduce
+new features are held for the next minor release.
+
+## How can I filter or select specific metrics?
+
+Telegraf has options to select certain metrics or tags as well as filter out
+specific tags or fields:
+
+- **Selectors** allow a user to include or exclude entire metrics based on the
+  metric name or tag key/pair values.
+- **Modifiers** allow a user to remove tags and fields based on specific keys,
+  with glob support.
+
+For more details and examples, see the [Metric Filtering][Metric Filtering]
+section in the docs.
+
+[Metric Filtering]: https://github.com/influxdata/telegraf/blob/master/docs/CONFIGURATION.md#metric-filtering
+
+## Could not find a usable config.yml, you may have revoked the CircleCI OAuth app
+
+This is an error from CircleCI during test runs.
+
+To resolve the error, you need to log back into CircleCI with your
+username/password if that is how you log in or if you use GitHub log, re-create
+your oauth/re-login with github.
+
+That should regenerate your token and then allow you to push a commit or close
+and reopen this PR and tests should run.
+
+## What does "Context Deadline exceeded (Client.Timeout while awaiting headers)" mean?
+
+This is a generic error received from Go's HTTP client. It is generally the
+result of a network blip or hiccup as a result of a DNS, proxy, firewall,
+and/or other network issue.
+
+The error should be temporary and Telegraf will recover shortly after without
+the loss of data.
+
+## How do I set the timestamp format for parsing data?
+
+Telegraf's `timestamp_format` config option requires the use
+[Go's reference time][go ref time] to correctly translate the timestamp. For
+example, if you have the time:
+
+```s
+2023-03-01T00:00:42.586+0800
+```
+
+A user needs the timestamp format:
+
+```s
+2006-01-02T15:04:05.000-0700
+```
+
+User's can try this out in the [Go playground][playground].
+
+[go ref time]: https://pkg.go.dev/time#pkg-constants
+[playground]: https://goplay.tools/snippet/hi9GIOG_gVQ
+
 ## Q: How can I monitor the Docker Engine Host from within a container?
 
 You will need to setup several volume mounts as well as some environment