Backoff policy stops if backoff iterator ends.

Previously if backoff iterator ended, backoff policy started to retry without any delay, now it stops.

Rename parallel to concurrent & update docs.

v0.5.0

Update doc

Add derives

v0.4.3

Add some derives

Add one more example to docs

v0.4.2

Add one more example in docs

Update docs

v0.4.1

Update docs

Update docs

v0.3.2

Update readme and docs

Update docs

v0.3.1

Update docs

Rename fns

v0.3.0

Rename fn

Rename fn

v0.2.0

Rename method

Remove wrong keyword from cargo.toml

v0.1.1

Bump version