vm_tools: sommelier: Fix small typo in README.md

BUG=none
TEST=none

Change-Id: I7416876b211b804432cb6d628158d8d95d6c5f85
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform2/+/3614636
Commit-Queue: Nic Hollingum <hollingum@google.com>
Reviewed-by: Nic Hollingum <hollingum@google.com>
Tested-by: Chloe Pelling <cpelling@google.com>
Auto-Submit: Chloe Pelling <cpelling@google.com>
diff --git a/vm_tools/sommelier/README.md b/vm_tools/sommelier/README.md
index 57c32d4..a6654f4 100644
--- a/vm_tools/sommelier/README.md
+++ b/vm_tools/sommelier/README.md
@@ -184,7 +184,7 @@
 forwarded to Linux programs by default so it won’t work when a Linux program
 has keyboard focus unless this shortcut is explicitly listed as an accelerator.
 
-Sommelier provides the `--accelerator=ACCELERATORS` flag for this purpose.
+Sommelier provides the `--accelerators=ACCELERATORS` flag for this purpose.
 `ACCELERATORS` is a comma separated list of accelerators that shouldn’t be
 forwarded to the Linux program but instead handled by the host compositor.
 Each accelerator can contain a list of modifiers (e.g. `<Control><Alt>`) and