zh-CN：Add the missing trans for 'get-involved/index.md' (#1972)
zh-CN：Add the missing trans for 'get-involved/index.md' (#1972)

1) 'Node.js Foundation calendar': This hasn't been translated into Chinese yet, so make up for that.
2) Fix some small trans for 'The DEV Community Node.js tag' part.

yous/new.nodejs.org,yous/new.nodejs.org,phillipj/new.nodejs.org,phillipj/new.nodejs.org,nodejs/new.nodejs.org,nodejs/new.nodejs.org