An optional `alt_text` parameter can be added when specifying a featured `image` in a page's front matter.
Alt text is used to describe the image when the page is read via a screen reader.
This commit also changes profile photo alt text from "avatar" to the person's name in alignment with major CMS and social sites.
Close#1592
If `site.Params.profile` is set to `true`, an author profile card will be displayed at the end of the page for every author (assuming that a profile has been setup for them under `content/authors/`).
Close#1481