[whatwg] Corrections for examples in section 3.14.10

[Ivo Emanuel Gonçalves]

On the examples:

"Vorbis audio alone in Ogg container

    <source src="audio.oga" type="audio/ogg; codecs=vorbis">

Speex audio alone in Ogg container

    <source src="audio.oga" type="audio/ogg; codecs=speex">"

This should be:

Vorbis audio alone in Ogg container

    <source src="audio.ogg" type="audio/ogg; codecs=vorbis">

Speex audio alone in Ogg container

    <source src="audio.spx" type="audio/ogg; codecs=speex">

Rationale: While Vorbis and Speex files (in Ogg) may use the .oga
extension, it is far more common to see them using .ogg and .spx
respectively.

Right below this section:

"Flac audio alone in Ogg container

    <source src="audio.oga" type="audio/ogg; codecs=flac">"

Should be:

FLAC audio alone in Ogg container

    <source src="audio.oga" type="audio/ogg; codecs=flac">

Rationale: The file extension is correct in the example.  The error is
in how FLAC is written, as FLAC is an acronym.  May be worth fixing
for correctness sake.

-Ivo