internal/frontend: generate https autolinks by default

This is a departure in behavior from the old markdown parser but it's
probably better to try https by default.

Change-Id: I0f06eda5b48e87200cd72a95daa08f54ce932749
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/550295
kokoro-CI: kokoro <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Jonathan Amsterdam <[email protected]>

Author: matloob

internal/frontend/markdown.go

@@ -50,13 +50,12 @@ func processReadmeMarkdown(ctx context.Context, readme *internal.Readme, info *s
 	}
 
 	p := markdown.Parser{
-		HeadingIDs:         true,
-		Strikethrough:      true,
-		TaskListItems:      true,
-		AutoLinkText:       true,
-		AutoLinkAssumeHTTP: true,
-		Table:              true,
-		Emoji:              true,
+		HeadingIDs:    true,
+		Strikethrough: true,
+		TaskListItems: true,
+		AutoLinkText:  true,
+		Table:         true,
+		Emoji:         true,
 	}
 	doc := p.Parse(readme.Contents)
 	(&linkRewriter{info, readme}).rewriteLinks(doc)