[Tour of Beam] Learning content for "IO Connectors" module (#25301)

* new format textIO

* fixes

* fixes

* add new units

* correct py example

* fixing structure and examples

* nonexistant category

* divide for write read

* add myfile.txt

* add licence to myfile.txt

* remove whitespace

* check multifile

* correct myfile

* comment go examples

* remove package

* comment kafka examples

* minor fix

* remove line and correct one line

* change names

* add Playground exercise

* correct kafka theory

* change folder name

* change golang examples

* correct formatter

* correct whitespace

* remove flags

* add txt files

* add excluded extensions

* change to trigger CI

* revert dummy commit

* correct kafka examples

* remove task tag

* correcr import

* change kafka example

* fixing task names

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Co-authored-by: oborysevych <oleg.borisevich@akvelon.com>
Co-authored-by: mende1esmende1es <mende1esmende1es@gmail.cp>