Add description of adding/removing a reaction to the README

1 files changed, 5 insertions, 0 deletions

diff --git a/README.md b/README.md
index 9dc0d64..79c50db 100644
--- a/README.md
+++ b/README.md
@@ -160,6 +160,11 @@ Delete previous message:
 s///
 ```
 
+Add a reaction to the nth last message. The number can be omitted and defaults to the last message. The `+` can be replaced with a `-` to remove a reaction instead.
+```
+3+:smile:
+```
+
 Turn off colorized nicks:
 ```
 /set plugins.var.python.slack_extension.colorize_nicks 0