Fixup Audio startup and add to documents

[drashna]

Description

#11553 changed the location that the audio startup code was called (eg the code that plays the startup chime), due to issues with timing issues with the suspend code for the board and the audio.

Unfortunately, this can cause the startup sound to simply not play at all, or to play a note or two, but nothing else. Reverting the change fixes the issue, but then potentially re-introduces the previous issue.

This adds a define that allows for users to choose between which situation, until a better fix can be found.

Types of Changes

• Core
• Bugfix
• Enhancement/optimization
• Documentation

Checklist

• My code follows the code style of this project: C, Python
• I have read the PR Checklist document and have made the appropriate changes.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• I have tested the changes and verified that they work and don't break anything (as well as I can manage).

[zvecr]

Fixup Audio startup

So the default behaviour is not the delayed startup that was added to fix stuff?
Any chance the PR could be updated with a little context as to the scenario this fixes? (just so we have something to point to later)

[sbmueller]

I'm still having trouble to get the startup sound back on my preonic. In my config.h:

#ifdef AUDIO_ENABLE
    #define STARTUP_SONG SONG(PREONIC_SOUND)
    // #define STARTUP_SONG SONG(NO_SOUND)

    #define DEFAULT_LAYER_SONGS { SONG(QWERTY_SOUND), \
                                  SONG(COLEMAK_SOUND), \
                                  SONG(DVORAK_SOUND) \
                                }
#endif

And in rules.mk:

AUDIO_ENABLE = yes

However I don't get a startup sound, even after explicitly hitting the key for enabling sound on the keyboard after flashing. Any idea what I'm missing?