More documentation on automatic PARALLELISM

[allipatev]

User guide states

If you do not know how to properly set PARALLELISM parameter, please leave it out, since the importer will calculate it automatically.

Please consider documenting the logic behind in more details, so that the following questions could be answered:

• What in general is taken into account for the calculation.
• A simplified formula.
• Will the automatic PARALLELISM protect my query from reaching Session heap limit and, therefore, failing?

[allipatev]

Table of Contents in the User guide seems to be incomplete/outdated.