internal/lsp/source: use space character in markdown formatting

Use space characters instead of the HTML " " character. VS Code and
other clients treat this character differently from a space, so it
results in different formatting. See
https://github.com/golang/go/issues/40947#issuecomment-680497904 for an
image with the difference.

Fixes golang/go#40947

Change-Id: Ia78cb3ba82dcca8303d1b5a0a6d359a3eaca837c
Reviewed-on: https://go-review.googlesource.com/c/tools/+/250697
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
diff --git a/internal/lsp/source/comment.go b/internal/lsp/source/comment.go
index 6a63fc0..4b86245 100644
--- a/internal/lsp/source/comment.go
+++ b/internal/lsp/source/comment.go
@@ -31,7 +31,7 @@
 var (
 	mdNewline   = []byte("\n")
 	mdHeader    = []byte("### ")
-	mdIndent    = []byte("&nbsp;&nbsp;&nbsp;&nbsp;")
+	mdIndent    = []byte("    ")
 	mdLinkStart = []byte("[")
 	mdLinkDiv   = []byte("](")
 	mdLinkEnd   = []byte(")")