Seems they recently stopped providing a htaccess file with the HTML5 Boilerplate, which is annoying, there was a lot of good stuff in there!
Fourtunatly, i have a copy, so here those rules…
# ----------------------------------------------------------------------
# | Media types |
# ----------------------------------------------------------------------
# Serve resources with the proper media types (f.k.a. MIME types).
#
# https://www.iana.org/assignments/media-types/media-types.xhtml
# https://httpd.apache.org/docs/current/mod/mod_mime.html#addtype
<IfModule mod_mime.c>
# Data interchange
AddType application/atom+xml atom
AddType application/json json map topojson
AddType application/ld+json jsonld
AddType application/rss+xml rss
AddType application/vnd.geo+json geojson
AddType application/xml rdf xml
# JavaScript
# Normalize to standard type.
# https://tools.ietf.org/html/rfc4329#section-7.2
AddType application/javascript js
# Manifest files
AddType application/manifest+json webmanifest
AddType application/x-web-app-manifest+json webapp
AddType text/cache-manifest appcache
# Media files
AddType audio/mp4 f4a f4b m4a
AddType audio/ogg oga ogg opus
AddType image/bmp bmp
AddType image/svg+xml svg svgz
AddType image/webp webp
AddType video/mp4 mp4 f4v f4p m4v
AddType video/ogg ogv
AddType video/webm webm
AddType video/x-flv flv
AddType audio/mpeg mp3
# Serving `.ico` image files with a different media type
# prevents Internet Explorer from displaying then as images:
# https://github.com/h5bp/html5-boilerplate/commit/37b5fec090d00f38de64b591bcddcb205aadf8ee
AddType image/x-icon cur ico
# Web fonts
AddType application/font-woff woff
AddType application/font-woff2 woff2
AddType application/vnd.ms-fontobject eot
# Browsers usually ignore the font media types and simply sniff
# the bytes to figure out the font type.
# https://mimesniff.spec.whatwg.org/#matching-a-font-type-pattern
#
# However, Blink and WebKit based browsers will show a warning
# in the console if the following font types are served with any
# other media types.
AddType application/x-font-ttf ttc ttf
AddType font/opentype otf
# Other
AddType application/octet-stream safariextz
AddType application/x-bb-appworld bbaw
AddType application/x-chrome-extension crx
AddType application/x-opera-extension oex
AddType application/x-xpinstall xpi
AddType text/vcard vcard vcf
AddType text/vnd.rim.location.xloc xloc
AddType text/vtt vtt
AddType text/x-component htc
</IfModule>