Add documentation for `HTTP::WebSocket#stream`

[meatball133]

I noticed this method didn't have any documentation and that it wasn't perhaps so self-explanatory. This is a draft; I haven't written more or less any language documentation before, so all feedback is appreciated.

[rusackas]

Ahh yes.. the crossfilter actually changes the data being fed to the table, so the total is calculated. The filter IN the table doesn't appear to recalculate on the fly. I'm sure it could if it had all the data, but if server pagination comes into play, that gets quite complicated.

Not sure if @justinpark 's planned migration to AG Grid would solve this.