Broken symlink in docs

[Eugene Leonovich]

Installing this library (as a dependency of amphp/parallel) through composer results in a broken symlink in the docs directory:

$ ls -la vendor/amphp/byte-stream/docs
lrwxrwxrwx. 1 gen gen   13 Dec 27 15:28 asset -> .shared/asset
...
drwxrwxr-x. 2 gen gen   40 Oct 22 21:37 .shared

$ ls -la vendor/amphp/byte-stream/docs/.shared
total 0
drwxrwxr-x. 2 gen gen  40 Oct 22 21:37 .
drwxrwxr-x. 3 gen gen 300 Oct 22 21:37 ..

This broken link causes Gitlab CI to generate a warning while buliding a project:

No URL provided, cache will be not downloaded from shared cache server. Instead a local version of cache will be extracted. 
WARNING: .../vendor/amphp/byte-stream/docs/asset: chmod .../vendor/amphp/byte-stream/docs/asset: no such file or directory (suppressing repeats) 

(see a related Gitlab issue).

[Niklas Keller]

Fixed via 6bbfcb6.

[Niklas Keller]

Released v1.5.1.