internal/span: fix a comment about windows drive letters

Change-Id: I24e7507d32fb5e76524ed6b9aeda225ccb11e861
Reviewed-on: https://go-review.googlesource.com/c/tools/+/339351
Trust: Robert Findley <rfindley@google.com>
Run-TryBot: Robert Findley <rfindley@google.com>
gopls-CI: kokoro <noreply+kokoro@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>
diff --git a/internal/span/uri.go b/internal/span/uri.go
index 2504921..a9777ff 100644
--- a/internal/span/uri.go
+++ b/internal/span/uri.go
@@ -45,7 +45,7 @@
 	if u.Scheme != fileScheme {
 		return "", fmt.Errorf("only file URIs are supported, got %q from %q", u.Scheme, uri)
 	}
-	// If the URI is a Windows URI, we trim the leading "/" and lowercase
+	// If the URI is a Windows URI, we trim the leading "/" and uppercase
 	// the drive letter, which will never be case sensitive.
 	if isWindowsDriveURIPath(u.Path) {
 		u.Path = strings.ToUpper(string(u.Path[1])) + u.Path[2:]