Release 4.0.3

• fix: handle trimming null/undefined header values (3ef8fcf)
• docs(small updates): fixed a few small grammar issues and copied readme to docs index (867bb63)
• Merge pull request #637 from Kikobeats/patch-1 (af0af4d)
• docs: get/set are sync methods (233ca2c)
• docs: docs cleanup and improvements (882bd73)
• build: call build in release task (c306dc0)
• Merge pull request #633 from igormartimiano/patch-1 (9646805)
• docs(readme.md): fix wrong import (0535a26)