Tag indexes use their own template (tagindex.tmpl)

via #930, thanks @punchagan (Puneeth Chaganti)

Signed-off-by: Chris “Kwpolska” Warrick <kwpolska@gmail.com>
document df7c741/#930

Signed-off-by: Chris “Kwpolska” Warrick <kwpolska@gmail.com>
changelog for #930/#933

Signed-off-by: Chris “Kwpolska” Warrick <kwpolska@gmail.com>
Merge pull request #933 from getnikola/tag-index-page-2

Use `tagindex.tmpl` if tag pages are indexes (via #930)