Update README (production) to include --no-experimental-fetch

[RafaPolit]

It is required to launch Uwazi with --no-experimental-fetch flag until we fix the implementation. The README instructions need to reflect this.

[RafaPolit]

Is this still required with NodeJS 20? cc @daneryl

[daneryl]

Probably yes, needs to be double checked, fetch is still experimental in node 20. fetch is stable in node 21, we probably need to fix whatever the problem is with node fetch and uwazi if we want to upgrade, unless the stable one is exactly the same functionality as the one we use now node-fetch

Do we have an issue with what is wrong with node fetch and uwazi?

[aphilop]

@RafaPolit @daneryl Is this still a critical bug? If yes, we have to deal with this somehow.