[Docs] Add bot usage

README.md

@@ -1,3 +1,6 @@
+For bot usage please see [here](docs/bot_usage_EN.md)
+---
+
 ## [👉Please join our Discord 请加入我们的Discord](https://discord.gg/N5P2uJD)
 
 ## 👇Clan War Standard 部落战标准规定

docs/bot_usage_EN.md

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+# Terminology
+* Person: An actual person. A person can have multiple accounts.
+* Account: A single account in the game, identified by the tag e.g. #2QLGU8XY. An account may not be in the clan.
+* Member: An account that is in the clan.
+
+* Alias: Shorthand for specifying an account. An account can have multiple aliases, but an alias can only belong to one account. Aliases are case-insensitive.
+* Main: The main account of a Person. A person will have exactly 1 Main.
+* Alt: An alternative account of a Person. A person can have multiple alts.
+
+```mermaid
+classDiagram
+
+    Person "1" --> "1" Main
+    Person "1" --> "*" Alt
+    Account "1" --> "*" Alias
+
+    Account <|-- Main
+    Account <|-- Alt
+
+    class Account {
+        is in clan: "Member"
+    }
+```