Revert wrong sync in 9aa18f61f2 [ci skip]

README.md

@@ -54,15 +54,6 @@ see [Building Ruby](doc/contributing/building_ruby.md)
 
 https://www.ruby-lang.org/
 
-## Configuration
-
-### Environment Variables
-
-- `NO_COLOR`: Assigning a value to it disables IRB's colorization.
-- `IRB_USE_AUTOCOMPLETE`: Setting it to `false` disables IRB's autocompletion.
-- `EDITOR`: Its value would be used to open files by the `edit` command.
-- `IRBRC`: The file specified would be evaluated as IRB's rc-file.
-
 ## Documentation
 
 - [English](https://docs.ruby-lang.org/en/master/index.html)