feat: corrected region names in table

[Kemi-Elizabeth]

Changed regions.html file and regions.md file

Why

Closes #4331

What's changed

So I had to correct the region names in the table on this page. I also had to correct the region names in the list below the Where REGION is one of the impacted regions section.

The region names were displayed as us-3.upsun.com for example, when they should be us-3.platform.sh regardless of whether it's on Upsun or Platform.sh.

Where are changes

I went into the regions.md file and replaced the shortcode with text so regions would change from ch-1.upsun.com to ch-1.platform.sh.

I also went into the regions.html file and changed the code class="!bg-snow">. In particular, I removed the code that was pulling in the site url automatically and just replaced that with text that said "platform.sh". It seemed like the easiest way to ensure it's hard coded and consistent across Upsun and Platform.sh.

I didn't change the Inbound IPs column in the table as that seemed correct. It points to an url ending platformsh.site. Can I confirm that's correct please?

Updates are for:

• platform (sites/platform templates)
• upsun (sites/upsun templates)

[gilzow]

This "situation" is a remnant of when the two docs were intertwined, and missed when they were separated. Since we're planning on restructuring docs anyway, I think hard-coding the platform.sh parts is perfectly acceptable.