Fixing outdated CustomRules.md

Lombiq.Analyzers.PowerShell/Rules/CustomRules.md

@@ -4,4 +4,4 @@ Our custom analyzer rules are automatically included when using `Invoke-Analyzer
 
 - `Measure-AutomaticVariableAlias`: Detects the usages of the alias `$_` of the automatic variable `$PSItem` and suggests to correct them.
 - `Measure-LineContinuation`: Detects the usages of the backtick (line continuation) character.
-- `Measure-VariableNameCasing`: Detects inconsistencies in the casing of parameter names and variable names (including automatic variables).
+- `Measure-VariableNameFormat`: Detects inconsistencies in the casing of parameter names and variable names (including automatic variables).