Add poll chat command with reaction voting

docs/communication.md

@@ -37,6 +37,7 @@ mention the puppet first.
 | `whitelist list` | Show the owner and the trusted users with their tiers. |
 | `whitelist add @user [user\|trusted\|admin]` | Add one or more users. The default tier is `user`. |
 | `whitelist remove @user` | Remove one or more users from the trust list. |
+| `poll <question> \| <opt 1> \| <opt 2> [\| opt 3 [\| opt 4]]` | Start a reaction poll. |
 
 Notes:
 
@@ -45,6 +46,21 @@ Notes:
 - `whitelist` commands need the admin tier.
 - The reply follows the response policy.
 
+## Polls
+
+The `poll` command posts a message and adds one number emoji per option. Discord users vote by
+reacting. The poll closes after `pollSeconds` (default 120) and the daemon posts the result.
+
+- Options: 2 to 4. Each option is at most 80 characters.
+- Emojis: `1️⃣`, `2️⃣`, `3️⃣`, `4️⃣`.
+- One vote per user. A new vote replaces the old vote.
+- Removing the reaction removes the vote.
+- The puppet's own reactions do not count.
+- Votes do not need a trust tier. Friends can vote.
+- The result message goes to the poll channel.
+
+Example: `@puppet poll Lunch? | Pizza | Sushi`
+
 ## Response policy
 
 The policy decides where a reply goes. Sensitive replies go by DM.