Updated MongoDB sample entries

Corrected docker-compose usage example

dump_table_ddl prints primary and foreign key constraints

- fixes the previous inability to print combined primary keys
- extends the ability to print foreign key constraints

adapted final exercise to dynamic queries content

Migrated ColumnStore exercises

- integrated postgraphile updates
- replaced BEGIN with std conforming START TRANSACTION

Updated monetdb conclusions and re-added query log files

Updated installation documentation and links

Unindented JSON output for better pdf output

Updated JSON input data for exercises

- added note on how to import using mongoimport
- double quoted keys
- added function to dump document structure
- changed to using %autofit on javascript/json output
- corrected join solution

updated mongo docker instances to version 4

Fixed Optimization document creation

- minor stylistic changes

Updated DistributedDB exercises

- minor restructuring of questions to better explain what to do
- automated db access logs of federated exercise

Moved useful note section upfront of exercise 3

Added missing logfile to print SQL statements

Updated solution variants of Two-Phase Commit

- Also updated introduction section related to databases.

Added more notes to the 2PC diagram

backported html document creation to be able to compare with latest

added nmbering to subtopics

- enabled costs logging for solutions

Finished update of indexes exercise