Update site_template/_includes/head.html.

* remove `chrome` from `X-UA-Compatible`; it's been discontinued
* remove unneeded end tags
* remove unneeded slash in `canonical` link
Merge pull request #2186 from XhmikosR/site_template
Update history to reflect merge of #2186 [ci skip]
docs: remove unused images.
Merge pull request #2187 from XhmikosR/rm-unused-img
Update history to reflect merge of #2187 [ci skip]