fix typos
switch type to context, closes #6
new section on request prioritization, closes #1
interaction with media queries, closes #11

- added examples in preload, prefetch, and Link header
- added note explaining intended behavior
bibliography file..
modified samples
Merge pull request #13 from yoavweiss/media_attribute_samples

Modified media attribute samples
update request matching

- reference 'fetch' algorithm
- request matching is *intentionally* ambiguous, as it depends on UA
  implementation and spec'ing this behavior is out of scope
first run at merging prefetch+prerender (#2)
note: request matching is not well defined #5
preload should not block load event
link to matching discussion
drop dns-prefetch to preconnect upgrade note
first run at required vs speculative execution (see #17)
issue ref for context
update readme
introduce probability attribute
replace context with fetch-settings attribute
use 'as' instead of 'fetch-settings'

- as is shorter and better at communicating the intent
- as does not require splitting source and destination context
- as does not require JSON parsing
- fetch-settings is still TBD as fetch is a work in progress

closes #21
add hint execution section

- hints do not block document load event
- document load and error events on link element