input: add "async" flag

Obviously, this has no effect on commands which do not support this
explicitly. A later commit will enable this for screenshots.

Also add some wording on mpv_command_async(), which has nothing to do
with this. Having a more elegant, unified behavior would be nice. But
the API function was not created for this - it's merely for running
commands _synchronously_ on the core, but without blocking the client
API caller (if the API user consistently uses only async functions).

1 files changed, 6 insertions, 0 deletions

diff --git a/DOCS/man/input.rst b/DOCS/man/input.rst
index 7dded1cca1..babfd1aacd 100644
--- a/DOCS/man/input.rst
+++ b/DOCS/man/input.rst
@@ -826,6 +826,12 @@ prefixes can be specified. They are separated by whitespace.
 ``repeatable``
     For some commands, keeping a key pressed doesn't run the command repeatedly.
     This prefix forces enabling key repeat in any case.
+``async``
+    Allow asynchronous execution (if possible). Note that only a few commands
+    will support this (usually this is explicitly documented). Some commands
+    are asynchronous by default (or rather, their effects might manifest
+    after completion of the command). The semantics of this flag might change
+    in the future. Set it only
 
 All of the osd prefixes are still overridden by the global ``--osd-level``
 settings.