Updates to .Net docs, generating a self-host token and .complete() note

[dean-journeyapps]

• .Net page now takes users to all .Net demo app examples instead of to the CLI demo repo.
• Added a note outlining the importance and potential repercussions of not calling .complete() in the uploadData() function.
• Added a comment next to the JWKS_URL parameter in the config.yaml file highlighting that it is not applicable if using Supabase
• Added link on "JOINS" to redirect to parameter query restrictions in the many-to-many sync rule guide.

[benitav]

Might also be good to add this to the main config skeleton https://docs.powersync.com/self-hosting/installation/powersync-service-setup#powersync-configuration and/or demo config which we also share from that main docs page https://github.com/powersync-ja/self-host-demo/blob/main/config/powersync.yaml, assuming this was added because users get confused by it

[dean-journeyapps]

Good catch, will do. Thank you!