Update analytics doc to include google-plugin-gtag

Summary

The existing docs about adding Google analytics recommend using the gatsby-plugin-google-analytics. Under the hood, this plugin uses Google’s analytics.js file.

However, Google has a guide recommending users upgrade to gtag.js instead. There is another plugin (gatsby-plugin-gtag) which uses gtag.js.

Motivation

The gtag.js file works with all Google services. Here are a few resources with more information about the difference between gtag.js and analytics.js:

• Google FAQ about gtag.js
• What’s the Difference Between analytics.js, gtag.js & ga.js? (Daan van den Bergh)

Steps to resolve this issue

• Update the Google analytics docs to add a section about “Using gatsby-plugin-gtag”.

Open a pull request

• Open a pull request with your work including the words “closes #27065” in the pull request description

[LekoArts]

@akgupta0777 When an issue can only be fixed by one PR (which is the case here) it’s common etiquette that a person offers their help and then picks up the work. This should be communicated clearly in the issue so that other people who want to help see that it’s already being addressed and not duplicate PRs are opened. To make things clearer we (“Gatsby”) assign issues to people then.

In the case of an issue being solvable by multiple PRs (e.g. “solve issue X around the docs”) the persons should all comment that they want to change things X,Y,Z so that - again - people are not doing duplicate work.

You can still help out by leaving review comments on the PR (although most of the time the core maintainers do that).

If the person who initially signed up for sending in a PR didn’t do that after quite some time (OSS is most of the times in the free time of people so don’t expect anyone to instantly create things) you could ask in the issue if you instead could pick it up (or any other person).

[akgupta0777]

@muescha It’s ok, not a problem.