build: update Makefile

docs/Makefile

@@ -10,9 +10,13 @@ h help:
 
 
 install:
-	pip install --upgrade pip
+	pip install pip --upgrade
 	pip install -r requirements.txt
 
+upgrade:
+	pip install pip --upgrade
+	pip install -r requirements.txt --upgrade
+
 
 s serve:
 	mkdocs serve --strict