docs: update tech insights with new backend instructions

[kurtaking]

Hey, I just made a Pull Request!

Provide updated documentation for implementing Tech Insights with the new backend system.

:heavy_check_mark: Checklist

• [ ] A changeset describing the change and affected packages. (more info)
• [ ] Tests for new functionality and regression tests for bug fixes
• [ ] Screenshots attached (for UI changes)
• [x] All your commits have a Signed-off-by line in the message. (more info)

[backstage-goalie[bot]]

Missing Changesets

The following package(s) are changed by this PR but do not have a changeset:

• @backstage-community/plugin-tech-insights-backend-module-jsonfc
• @backstage-community/plugin-tech-insights-backend

See CONTRIBUTING.md for more information about how to add changesets.

Changed Packages

Package Name	Package Path	Changeset Bump	Current Version
@backstage-community/plugin-tech-insights-backend-module-jsonfc	workspaces/tech-insights/plugins/tech-insights-backend-module-jsonfc	none	v0.1.55
@backstage-community/plugin-tech-insights-backend	workspaces/tech-insights/plugins/tech-insights-backend	none	v0.6.2

[BethGriggs]

Closing and reopening for CI issue (which should now hopefully be fixed by https://github.com/backstage/community-plugins/pull/875)

[04kash]

It seems that the CI is failing due to prettier checks

[kurtaking]

@Xantier @nickboldt, can you approve the workflow and provide a review? Thanks!