blogposts: add some comments

blogposts/post.go

@@ -12,6 +12,13 @@ type Post struct {
 	Tags                     []string
 }
 
+// TODO: Split a metadata line into 2 parts, one is the key, another is the
+// value, check if the key exists in the key map (ex. Title, Description etc.)
+// If not exist, then ignore this metadata line.
+//
+// WARN: What if a file doesn't have metadata, just pure Markdown ??
+// We can control if we at least found title line. If at the end, it is not
+// present, we consider that the post has an error.
 const (
 	titleLine       = "Title: "
 	descriptionLine = "Description: "