README out of date with build instructions

[knolleary]

Description

PR #5177 changed how the website incorporates docs from the flowfuse/flowfuse repo. There are some outstanding problems:

.claude/CLAUDE.md was updated with information about the new process - but README.md was not updated and contains out of date information.

Specifically, the fact it now clones the ff repo by default rather than use a local copy of the docs without manual intervention. This has broken the FF repo build that verifies doc changes.

It has also added docs to CLAUDE.md about an npm task called dev:nuxt. This task doesn't exist.

It has also removed the ability to watch the docs for changes and trigger automatic rebuild - was previously the npm run dev:docs task. When working on product docs, I now have to manually restart the website build every time and wait for it to complete.

I also find I'm routinely hitting nuxt/nuxt#35253 due to the version of nuxt we are using.

In addition to knowing about the FLOWFUSE_DOCS_LOCAL env var, I also have to set TMPDIR=/tmp to workaround that nuxt issue.

Epic/Story

No response

Have you provided an initial effort estimate for this issue?

I have provided an initial effort estimate

[dimitrieh]

Created two PR's to speed this up/take some work out of the hands of engineers ideally (should be merged in order):

1. Resolve product docs from the caller's checkout #5473
2. Re-enable the documentation checks flowfuse#8024

Checking CI as we speak