Update adding-analytics.md

[im-adithya]

Description

Gatsby uses gatsby-plugin-google-gtag instead of gatsby-plugin-gtag. Hence the doc needed to be updated.
This PR closes #27623

[pfortes]

That was fast! Thanks @im-adithya,
I think this little change can be super good for new users looking at how to use gtag correctly with gatsby.

[im-adithya]

@LekoArts @meganesu Can you please merge this as Hacktoberfest is going to end 🥺

[meganesu]

@im-adithya I haven't gotten a chance to review this in detail yet, but I added the hacktoberfest-accepted label in the meantime so that you should be able to get credit.

[Miyou]

What about the plugin gatsby-plugin-google-analytics? What's the difference? Can't find any info about which one to use which is very confusing.

[pfortes]

What about the plugin gatsby-plugin-google-analytics? What's the difference? Can't find any info about which one to use which is very confusing.

I will try to explain,
gatsby-plugin-google-analytics uses analytics.js which is the old code from google and is an oficial gatsby plugin.
gatsby-plugin-google-gtag uses the gtag script (new one and the one you should use) this is also an oficial plugin.

gatsby-plugin-gtag is not a oficial plugin.

[pvdz]

lgtm, thank you 💜

[Miyou]

What about the plugin gatsby-plugin-google-analytics? What's the difference? Can't find any info about which one to use which is very confusing.

I will try to explain,
gatsby-plugin-google-analytics uses analytics.js which is the old code from google and is an oficial gatsby plugin.
gatsby-plugin-google-gtag uses the gtag script (new one and the one you should use) this is also an oficial plugin.

gatsby-plugin-gtag is not a oficial plugin.

Thanks! That makes a lot of sense. Maybe it is obvious for those who know that there are two different google analytics scripts, but for someone who didn't I really couldn't figure out the difference.