Update static.rst documentation

[kavi2du]

This PR updates the documentation of the static.py to reflect the new web platform insert system and deployment configuration.

Addresses the missing documentation for the recently introduced asset-gathering strategy, which is currently not documented at all.

Refs #2337 , #2442

PR Checklist:

• [ x ] All new features have been tested
• [ x ] All new features have been documented
• [ x ] I have read the CONTRIBUTING.md file
• [ x ] I will abide by the code of conduct

[kavi2du]

@freakboy3742 Hi Russel, I just updated the documentation for static.py to reflect the new web platform insert system and deployment configuration. Could you please take a quick look and let me know if it’s clear enough, or if it needs more detail?

[freakboy3742]

Great work - I've pushed some editorial tweaks (mostly minor tweaks and reorganisation, plus dropping the section on legacy support that we don't want to encourage the use of), but you gave me a really solid first draft to work from.