Remove stats.md

- Perf result is saved in the PR, don't need a file here forever

stats.md

@@ -1,49 +0,0 @@
-## Performance Stats
-
-#### drupal (-27%)
-```
-old parser: 42.2
-new parser: 30.8
-```
-
-#### wordpress (-33%)
-```
-old parser: 3.6
-new parser: 2.4
-```
-
-#### php-language-server (-17%)
-```
-old parser: 13.3
-new parser: 11.0
-```
-
-#### tolerant-php-parser (+59%)
-```
-old parser: 3.7
-new parser: 5.9
-```
-
-#### math-php (-35%)
-```
-old parser: 1.7
-new parser: 1.1
-```
-
-#### symfony (-23%)
-```
-old parser: 18.2 
-new parser: 14.1
-```
-
-#### CodeIgniter (-23%)
-```
-old parser: 1.8
-new parser: 1.1
-```
-
-#### cakephp (-24%)
-```
-old parser: 5.1
-new parser: 3.9
-```