Is your feature request related to a problem? Please describe.
The field name ttl used in FeatureView is misleading.
Time to Live (TTL) is a well known term that defines a mechanism to automatically expire database records. In Redis, for example, the command EXPIRE defines a time to live for a given key.

When I used that FeatureView.ttl configuration for the first time, I expected to set some expiration time (or TTL) for keys written into online stores. The documentation states something like this here.

The amount of time this group of features lives. A ttl of 0 indicates that this group of features lives forever.

However FeatureView's TTL is not used in that way. It's used to define start_date to extract data from offline store during materialization step here. The actual key ttl configuration used to expire entities is key_ttl_seconds at online store level here.

I had to explain this sometimes to different people because of this misunderstanding. I think this is also kind of mentioned here and here.

Describe the solution you'd like
My suggestion is renaming this field to something like materialization_lookback_interval, lookback_interval or lookback_delta since this is the actual meaning of this configuration as far as I understand. Also update docs accordingly.