Chapter Review(Ping): TensorFlow.js

[huan]

Reviews from @pyu10055

• [x] add the WeChat plugin support in the overview
• [x] the converter params have changed, check 1.x doc
• [x] check tfjs-node documentation, see if commands are up to date
• [x] the performance numbers are old I will send you a new one.
• [x] 在CPU上需要时间为97ms where is these numbers coming from?

TensorFlow.js Chapter: #6

[huan]

Close this issue because I believe they are good now.