Host URL selector for examples is not very visible

While reviewing code examples for `influxdb3-go` I noticed the Host URL selector at the top of the page, which updates _host_ values in code examples. This is very nice.

However, when I reach the code examples in the page, the control is no longer visible at the top of the page. Additionally it is a bit hidden for first time users. Further there is no _on_hover_ hint explaining what the cogwheel control is for.

It might be nicer to have this control on the right hand margin along with the date picker and the AI link. It would be more visible there.

_the cogwheel_

_the selector_

_the example code_

##### Relevant URLs
- https://docs.influxdata.com/influxdb3/cloud-serverless/get-started/write/?t=Go

Start at the linked write page and inspect how the Host URL selector is rendered and how it relates to the date picker and AI link. Confirm the selector remains visible while reading examples, is easier for first-time users to discover, and has a hover hint explaining the cogwheel control.

Written by the indexing model from the issue text.