Restructure the documentation

[rekjuh]

As discussed 15.4.2025:

The new structure would be:

1. Introduction
   Inc. the following parts from Application framework:
   2.1 framework,
   2.2. frontend,
   2.4. backend and
   2.4.1 for the section which describes Oskari backend as an application that can be customized for a specific need.

"The backend architecture in oskari-server Maven-modules ..." from 2.4.1 goes to section 5.

2. Setup
   The Updating instructions will be moved to section 11)

3. Frontend framework

Inc. 2.3 Frontend bundle implementation convention

4. Server application
   inc. Oskari-server Maven modules from 2.4.1.
   inc. authentication in general

5. Functionalities
   inc. section "Other functionalities"
   inc. configuration instructions for each functionality
   inc. authentication/registeration of the end-user

6. Operating instructions

7. Developing instructions
   inc. Git branches from Introduction)

8. Configuration instructions8.

9. Enabling modules

10. Updating

11. Application troubleshooting

12. Changelog

RPC will have its own section or header. No place for it as of yet. The RPC section should contain the following: https://oskari.org/documentation/api/bundles/latest/RPC

Other changes: The H3 level of headers will be removed from navigation (1.1.1., 2.1.3. etc)

[ZakarFin]

Removal of h3 oskariorg/oskari-documentation-site#185