Audio: Document channel order convention

This patch restores the documentation on the channel order convention
that was present in the Audio HAL 2.0 but remove by mistake in 4.0.

This is a vendor feedback.

Test: mm
Bug: 133453897
Change-Id: I8eabd8883612d39ced21481fc44661b0808754bb
Signed-off-by: Kevin Rocard <krocard@google.com>
diff --git a/current.txt b/current.txt
index e6ac705..d572f21 100644
--- a/current.txt
+++ b/current.txt
@@ -428,6 +428,7 @@
 1b0500367ed2b32a841667ac3200edf3d3a164e8004aca445ff1b085ac831e93 android.hardware.audio@5.0::IStreamOutCallback
 83e365479cc77d8717c155e1787ee668cd2ae4c557b467cf75b8e7cd53697ad8 android.hardware.audio@5.0::types
 07d17800b298331e90d4ea5d8ba19a1ae3fe9c1dbff08d9f75fd3ade09496d67 android.hardware.audio.common@5.0::types
+b3c1ec989f317b9a36eac10f4e7b66aad2997302156899481553a67476e148dd android.hardware.audio.common@5.0::types # b/133453897
 f269297866765b95ddd1825676cc8a772f0c7c9863286df596fc302781a42ff5 android.hardware.audio.effect@5.0::IAcousticEchoCancelerEffect
 fa187b602d8939644ef708ed7627f2e3deac97899a4bda1de07f2ff126abe243 android.hardware.audio.effect@5.0::IAutomaticGainControlEffect
 e1bf864ccb8458c0da1dcc74a2e748b1dca8ac360df590591cf82d98292d7981 android.hardware.audio.effect@5.0::IBassBoostEffect