feat: add meta tag

exe/yamd

@@ -91,6 +91,23 @@ class HTMLRenderer < YAMD::Renderer
 		}
 	end
 
+	def single_tag(name, **attrs)
+		@buf << "<#{name}"
+		attrs.each { |k, v|
+			@buf << " "
+			if k.kind_of? Symbol
+				k = k.to_s
+			end
+			@buf << k
+			@buf << "=" << v.dump
+		}
+		@buf << "/>"
+	end
+
+	def meta(name, value)
+		single_tag('meta', name: name, content: value)
+	end
+
 	def tag(name, **attrs)
 		@buf << "<#{name}"
 		attrs.each { |k, v|