Release SkyWalking PHP 0.8.0 (#123)

Release SkyWalking PHP 0.7.0 (#96)

Release SkyWalking PHP Agent 0.6.0 (#89)

Bump to 0.5.0. (#72)

Bump to 0.4.0. (#59)

Bump to 0.3.0. (#51)

Bump to 0.2.0. (#34)

Update official documentation link. (#11)