WIP: Generate README.md from template

[mahnunchik]

According to the logic behind the template https://github.com/flyte/mqtt-io/blob/develop/README.md.j2 README should be generated from this template.

I've tried to generate it but there are a lot of changes.

• I was able to fix some huge changes by separating module description and samples to two comment blocks.
• It seems it was edited manually before.
• There are two READMEs with the different content https://github.com/flyte/mqtt-io/blob/develop/README.md and https://github.com/flyte/mqtt-io/blob/develop/docs_src/README.md

I think the template should be modified to match actual README.

[mahnunchik]

Two comments broke linting...

Maybe examples of using should be moved out of source files?

@flyte @mschlenstedt @BenjiU I need help to figure out how to fix readme generation.