Update documentation: Placement of JavaScript tracker code

[utrenkner]

This had me quite confused - please update the documentation to reflect the new recommendation.

During the installation I thought I read "We recommend to paste it immediately before the closing tag.".

But my colleague - who had implemented Piwik in our other sides - placed it, as usual, before the closing tag. Therefore, I wanted to verify what the recommendation was and found https://piwik.org/docs/installation/#install-the-javascript-tracking-tag , which still has the old recommendation.

I then went back to make another install on a test system just to be sure what I had read there.

[tsteur]

Thanks! This FAQ is outdated indeed.

[tsteur]

Maybe also related is #9776 and eg yawik/DemoSkin#1 etc

[mattab]

Thanks for the suggestion. The user guide https://piwik.org/docs/installation/#install-the-javascript-tracking-tag has been updated with our latest recommendation (paste the code immediately before the </head> tag)