updating changelogs and version to 1.2.0, 0.21b0 (open-telemetry#1841)

updating changelogs and version to 1.2.0, 0.21b0 (open-telemetry#1841)

Release 1.1.0/0.20b0 (open-telemetry#1783)

fix build script

preparing 1.0.0/0.19b0 release (open-telemetry#1718)

preparing 1.0.0/0.19b0 release (open-telemetry#1718)

Release for 0.18b0 (open-telemetry#1610)

Release for 1.0.0rc1 (open-telemetry#1601)

rename instrumentation to shim (open-telemetry#1539)

[pre-release] Update changelogs, version [0.16b1] (open-telemetry#1427)