gopls/internal/protocol/semtok: instructions for modifier/type changes

Gopls now honors the modifiers sent by the language client and only
returns modifiers if the language client supports them.

When gopls add / delete custom modifiers, the vscode-go should be
updated as well to keep in sync.

For golang/go#80736

Change-Id: Ib08d5a37f7e6ff8aceb1c06513b2da7f1d879303
Reviewed-on: https://go-review.googlesource.com/c/tools/+/811140
Auto-Submit: Hongxiang Jiang <hxjiang@golang.org>
LUCI-TryBot-Result: golang-scoped@luci-project-accounts.iam.gserviceaccount.com <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Alex Putman <aputman@golang.org>

gopls/internal/protocol/semtok/semtok.go

diff --git a/gopls/internal/protocol/semtok/semtok.go b/gopls/internal/protocol/semtok/semtok.go
index 9ef3d30..f384f36 100644
--- a/gopls/internal/protocol/semtok/semtok.go
+++ b/gopls/internal/protocol/semtok/semtok.go
@@ -44,6 +44,9 @@
 	//
 	// If you move types to above, document it in
 	// gopls/doc/features/passive.md#semantic-tokens.
+	//
+	// Sync any changes below with the vscode-go custom token type list.
+	// See: extension/src/language/goSemanticTokens.ts
 	// TokClass      Type = "class"
 	// TokDecorator  Type = "decorator"
 	// TokEnum       Type = "enum"
@@ -103,6 +106,9 @@
 	// Since the type of a symbol is orthogonal to its kind,
 	// (e.g. a variable can have function type),
 	// we use modifiers for the top-level type constructor.
+	//
+	// Sync any changes below with the vscode-go custom token modifier list.
+	// See: extension/src/language/goSemanticTokens.ts
 	ModArray     Modifier = "array"
 	ModBool      Modifier = "bool"
 	ModChan      Modifier = "chan"