Removed deprecated UnusedPrivateElementsSniff

Author: kukulich

README.md

@@ -290,21 +290,6 @@ Requires using combined assignment operators, eg `+=`, `.=` etc.
 
 ### Cleaning - detecting dead code
 
-#### SlevomatCodingStandard.Classes.UnusedPrivateElements 🚧
-
-**DEPRECATED**
-See https://phpstan.org/blog/detecting-unused-private-properties-methods-constants
-
-Although PHP_CodeSniffer is not suitable for static analysis because it is limited to analysing one file at a time, it is possible to use it to perform certain checks. `UnusedPrivateElementsSniff` checks for unused methods, unused or write-only properties in a class and unused private constants. Reported unused elements are safe to remove.
-
-This is very useful during refactoring to clean up dead code and injected dependencies.
-
-Sniff provides the following settings:
-
-* `alwaysUsedPropertiesAnnotations`: mark certain properties as always used, for example the ones with `@ORM\Column`
-* `alwaysUsedPropertiesSuffixes`: mark properties with name ending with a certain string to be always marked as used
-* `alwaysUsedMethodsAnnotations`: mark certain methods as always used, for example the ones with `@Serializer\PostDeserialize`
-
 #### SlevomatCodingStandard.Functions.UnusedInheritedVariablePassedToClosure 🔧
 
 Looks for unused inherited variables passed to closure via `use`.