Remove 3.0 README notice

Author: sirbrillig

README.md

@@ -4,8 +4,6 @@
 
 Plugin for PHP_CodeSniffer static analysis tool that adds analysis of problematic variable use.
 
-**Please note that this README is for VariableAnalysis v3. For documentation about v2, [see this page](https://github.com/sirbrillig/phpcs-variable-analysis/blob/2.x-legacy/README.md).**
-
 - Warns if variables are used without being defined. (Sniff code: `VariableAnalysis.CodeAnalysis.VariableAnalysis.UndefinedVariable`)
 - Warns if variables are used for an array push shortcut without being defined. (Sniff code: `VariableAnalysis.CodeAnalysis.VariableAnalysis.UndefinedArrayVariable`)
 - Warns if variables are used inside `unset()` without being defined. (Sniff code: `VariableAnalysis.CodeAnalysis.VariableAnalysis.UndefinedUnsetVariable`)