Update LSP status doc (rename is complete + tested in VS Code)

Change-Id: Ifce985123efcfec658218c3a4fbe4b6a2102b0bc
Reviewed-on: https://dart-review.googlesource.com/c/89544
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Commit-Queue: Danny Tuppeny <dantup@google.com>
diff --git a/pkg/analysis_server/tool/lsp_spec/README.md b/pkg/analysis_server/tool/lsp_spec/README.md
index fe5bf80..2ef56cb 100644
--- a/pkg/analysis_server/tool/lsp_spec/README.md
+++ b/pkg/analysis_server/tool/lsp_spec/README.md
@@ -70,7 +70,7 @@
 | textDocument/formatting | ✅ | ✅ | ✅ | ✅ |
 | textDocument/rangeFormatting | | | | | requires support from dart_style?
 | textDocument/onTypeFormatting | ✅ | ✅ | ✅ | ✅ |
-| textDocument/rename | ✅ | ✅ | Incomplete! | |
+| textDocument/rename | ✅ | ✅ | ✅ | ✅ |
 | textDocument/prepareRename | | | | |
 | textDocument/foldingRange | | | | |