changelog for signature help piped expressions fix

Author: zth

CHANGELOG.md

@@ -20,6 +20,8 @@
 
 - Adapt command to create interface files to latest JSX V4 (no key prop, possibly empty record) https://github.com/rescript-lang/rescript-vscode/issues/617
 
+- Fix issue where pipes were not taken into account in the signature help, resulting in the highlighted argument in signature help always being off by one for unlabelled arguments in piped expressions https://github.com/rescript-lang/rescript-vscode/issues/618
+
 ## v1.8.2
 
 #### :rocket: New Feature