[Docs] Add definitions of terms used in results

[mikemaccana]

Describe the bug

Börje Karlsson mentioned I should file this bug on Hacker News.

I'm an active user of this library - thanks for making it! One piece of feedback is: the documentation https://github.com/Microsoft/Recognizers-Text/tree/master/Ja... doesn't seem to cover the the various terms used in the results.

Specifically

• What is a culture? The type is string - English seems to work (I found it in an example) but I'm not sure. Maybe en-GB would be better,
• What are the items in the array returned from recognizeDateTime.
• What is a resolution?
• What are start and end?
• Is the best resolution always first?
• Is there some way to make resolution always be in the past? Or the future? Eg if I have a list of transactions (in the past) I would want 'October' to only resolve to last October. If I am filling in a delivery date, I want 'October' to always be in the future.

The README for the JS package doesn't seem to cover what these are, so I'm currently just guessing.

My code currently contains this:

    // TODO: what does recognizeDateTime() actually return
    // Feels like these are the 'recognisable entities' that were found but I can't find docs.
    const recognizedDateTimeEntities = recognizeDateTime(
      filterValue,
      // This is just 'string' in the types but it seems to work.
      // TODO: find docs, check if this is valid.
      "English"
    );
    if (recognizedDateTimeEntities.length) {
      const firstEntity = recognizedDateTimeEntities[0];
      // TODO: what is a resolution?
      // Guessing this is each possible value for each recognisable item but I can't find docs.
      // eg if the user enters 'october'
      // values[0] is in the past
      // values[1] is in the future
      // we always want the past, hence picking 0.
      const firstResolution = firstEntity?.resolution?.values[0] || null;
      ...

Expected behavior
Either docs covering the various terms used in recognizedDateTime() output in the README, or a link to somewhere else if this documentation is there instead.

Platform (please complete the following information):

• Platform: JavaScript
• Environment: npm
• Version of package: 1.3.0