Merge pull request #1869 from hackmdio/fix/readme-typo

typo: opened source -> open sourced

Author: Yukaii

README.md

@@ -39,7 +39,7 @@ HackMD is built with one promise - **You own and control all your content**:
 
 ## CodiMD - The Open Source HackMD
 
-CodiMD is the free software version of [HackMD](https://hackmd.io), developed and opened source by the HackMD team with reduced features (without book mode), you can use CodiMD for your community and own all your data. *(See the [origin of the name CodiMD](https://github.com/hackmdio/hackmd/issues/720).)* 
+CodiMD is the free software version of [HackMD](https://hackmd.io), developed and open sourced by the HackMD team with reduced features (without book mode), you can use CodiMD for your community and own all your data. *(See the [origin of the name CodiMD](https://github.com/hackmdio/hackmd/issues/720).)* 
 
 CodiMD is perfect for open communities, while HackMD emphasizes on permission and access controls for commercial use cases.