docs(README): add rule customItemDiscardTime

Author: OptiJava

README-en.md

@@ -255,6 +255,14 @@ Prevent CCE Suppression Crashes，watch [Void0's bilibili video](https://www.bil
 - Acceptable value: `true` `false`
 - Categories: `BugFix` `Experimential`
 
+### customItemDiscardTime
+
+Custom item discard time. :)
+
+- Default value: `false`
+- Acceptable value: `true` `false`
+- Categories: `Feature`
+
 ## Command
 
 ### player xxx tp

README.md

@@ -262,6 +262,14 @@ CommandLogger.json配置文件可以配置白名单、黑名单等，修改配
 - Acceptable value: `true` `false`
 - Categories: `BugFix` `Experimential`
 
+### customItemDiscardTime
+
+自定义物品消失时间
+
+- Default value: `false`
+- Acceptable value: `true` `false`
+- Categories: `Feature`
+
 ## Command
 
 ### player xxx tp