Add changelog entry

CHANGELOG.md

@@ -28,6 +28,7 @@
   - refactored the codebase with a new architecture which allows dynamic feature, document widget adapter, and code editor registration ([#318])
   - the document in the connections list in the statusbar popover are now represented by easy-to-understand DocumentLocator (breadcrumbs) widget rather than an internal id ([bacc006])
   - syntax highlighting mode is adjusted to the language with the majority of the code in an editor ([#319])
+  - copy diagnostics message and filter diagnostics from context menu of Diagnostic Panel ([#330])
 
 - bug fixes
 
@@ -45,6 +46,7 @@
 [#319]: https://github.com/krassowski/jupyterlab-lsp/pull/319
 [#322]: https://github.com/krassowski/jupyterlab-lsp/pull/322
 [#329]: https://github.com/krassowski/jupyterlab-lsp/pull/329
+[#330]: https://github.com/krassowski/jupyterlab-lsp/pull/330
 [00448d0]: https://github.com/krassowski/jupyterlab-lsp/pull/318/commits/00448d0c55e7f9a1e7e0a5322f17610daac47dfe
 [bacc006]: https://github.com/krassowski/jupyterlab-lsp/pull/318/commits/bacc0066da0727ff7397574914bf0401e4d8f7cb
 [4e5b2ad]: https://github.com/krassowski/jupyterlab-lsp/pull/318/commits/4e5b2adf655120458cc8be4b453fe9a78c98e061