Fix ToC links (#289)

Author: theofidry

README.md

@@ -55,7 +55,9 @@ potentially very difficult to debug due to dissimilar or unsupported package ver
         - [Step 2: Run PHP-Scoper](#step-2-run-php-scoper)
 - [Recommendations](#recommendations)
 - [Limitations](#limitations)
-    - [PSR-0 support](#psr-0-support)
+    - [Dynamic symbols](#dynamic-symbols)
+    - [Heredoc values](#heredoc-values)
+    - [Callables](#callables)
     - [String values](#string-values)
     - [Native functions and constants shadowing](#native-functions-and-constants-shadowing)
     - [Grouped constants whitelisting](#grouped-constants-whitelisting)