[BUG] Documentation on form encoded serializer incomple

[envimate-opensource]

Describe the bug
Documentation on form encoded serializer is incomple.

To Reproduce
Have someone who did not implement the feature try to understand what this feature does and how to use it only by reading the features documentation

Expected behavior
Have someone who did not implement the feature understand what this feature does and how to use it only by reading the features documentation

Additional context
The docs should contain how to setup and usage of the serializer and deserializer