amixer: Expand on channel docs in man page

[GitHub pull_request - opened]

alsa-project/alsa-utils pull request #78 was opened from mcampbellizo:

Add missing channel params to the amixer man page. Also call out that
the channel param must come before the value to take effect.

signed-off-by: Matthew Campbell <mcampbell at izotope.com>

Request URL   : https://github.com/alsa-project/alsa-utils/pull/78
Patch URL     : https://github.com/alsa-project/alsa-utils/pull/78.patch
Repository URL: https://github.com/alsa-project/alsa-utils