Docs: Update `.htaccess` related info and links
Docs: Update section about the X-UA-Compatible meta option

Chrome Frame is not supported anymore and we removed the option in
8fc2650.
This commit removes the documentation about Chrome Frame in the
X-UA-Compatible meta tag docs.

Related to #1396.
Further optimize the apple touch icons

Reduce the total size of the icons by 172 bytes using zopfli.

Close #1415.
Compress .png files losslessly.

Use zopfli-png with 1000 iterations, pngout /r with various blocksizes and deflopt.

The total difference is -320 bytes.