DOC: Add sections to documentation

Summary

See https://gitlab.indiscale.com/caosdb/customers/lfpb/management/-/issues/409. Add sections, placeholders for examples, and automatically generated docs to the documentation.

Focus

Verify that the structure makes sense.

Test Environment

Build the documentation as described in README_SETUP.md

Check List for the Author

Please, prepare your MR for a review. Be sure to write a summary and a focus and create gitlab comments for the reviewer. They should guide the reviewer through the changes, explain your changes and also point out open questions. For further good practices have a look at our review guidelines

• All automated tests pass
• Reference related Issues
• [ ] Up-to-date CHANGELOG.md
• Annotations in code (Gitlab comments)
  • Intent of new code
  • Problems with old code
  • Why this implementation?

Check List for the Reviewer

• I understand the intent of this MR
• All automated tests pass
• [ ] Up-to-date CHANGELOG.md
• The test environment setup works and the intended behavior is reproducible in the test environment
• In-code documentation and comments are up-to-date.
• Check: Are there spezifications? Are they satisfied?

For further good practices have a look at our review guidelines.

docs/src/examples.md

+# Examples
+
+**TODO** Fill the sections below once the parts have been implemented.
+
+## Connect to a CaosDB server
+
+See also the hints on the [Installation](@ref) and set-up of
+CaosDB.jl. CaosDB.jl makes use of the C++ client of CaosDB, so in
+order to connect to a CaosDB server you first have to configure the
+connection via a configuration file as explained in the [documentation
+of CaosDB's C++
+client](https://docs.indiscale.com/caosdb-cpplib). Once the
+configuration is set up, connecting to the server is as easy as
+
+```julia
+using CaosDB
+connection = CaosDB.Connection.connect()
+```
+
+which will establish a connection and print the version of the server
+you are connected to.
+
+## Retrieve a Record
+
+## Execute queries
+
+## Insert, update, and delete entities
+
+## Download a file