drop attachment:// proto, improve docs

Removed attachment:// proto from docs, back compatibility is saved.
Now using the implementatin of `Attachment:` provided by @csoutherland.

Removed a bunch of swear stuff from docs, oh boy I was so frustrated at
that time.

pkg/mark/attachment.go

@@ -186,16 +186,40 @@ func CompileAttachmentLinks(markdown []byte, attaches []Attachment) []byte {
 	})
 
 	for _, replace := range replaces {
-		from := replace
 		to := links[replace]
 
-		log.Debugf(nil, "replacing: %q -> %q", from, to)
+		found := false
+		if bytes.Contains(markdown, []byte("attachment://"+replace)) {
+			from := "attachment://" + replace
 
-		markdown = bytes.ReplaceAll(
-			markdown,
-			[]byte(from),
-			[]byte(to),
-		)
+			log.Debugf(nil, "replacing legacy link: %q -> %q", from, to)
+
+			markdown = bytes.ReplaceAll(
+				markdown,
+				[]byte(from),
+				[]byte(to),
+			)
+
+			found = true
+		}
+
+		if bytes.Contains(markdown, []byte(replace)) {
+			from := replace
+
+			log.Debugf(nil, "replacing link: %q -> %q", from, to)
+
+			markdown = bytes.ReplaceAll(
+				markdown,
+				[]byte(from),
+				[]byte(to),
+			)
+
+			found = true
+		}
+
+		if !found {
+			log.Warningf(nil, "unused attachment: %s", replace)
+		}
 	}
 
 	return markdown

pkg/mark/meta.go

@@ -11,12 +11,11 @@ import (
 )
 
 const (
-	HeaderParent          = `Parent`
-	HeaderSpace           = `Space`
-	HeaderTitle           = `Title`
-	HeaderLayout          = `Layout`
-	HeaderAttachment      = `Attachment`
-	HeaderExactAttachment = `ExactAttachment`
+	HeaderParent     = `Parent`
+	HeaderSpace      = `Space`
+	HeaderTitle      = `Title`
+	HeaderLayout     = `Layout`
+	HeaderAttachment = `Attachment`
 )
 
 type Meta struct {
@@ -89,9 +88,6 @@ func ExtractMeta(data []byte) (*Meta, []byte, error) {
 			meta.Layout = strings.TrimSpace(value)
 
 		case HeaderAttachment:
-			meta.Attachments["attachment://"+value] = value
-
-		case HeaderExactAttachment:
 			meta.Attachments[value] = value
 
 		default: