Unify indentation in configuration files

[vdusek]

Some of our configuration files currently use 2 space indent and others use 4 space indent.

Let's unify this and use the same indent (2 spaces) for all configuration files (yaml, toml, ini, ...).

[vdusek]

We're gonna use 2 space indent for YAML and 4 for all other file types as was discussed in apify/apify-client-python#139.