enhance: add a warning on demo graph not being persisted

resources/css/common.css

@@ -924,7 +924,7 @@ a.chosen {
 }
 
 a.warning,
-span.warning {
+span.warning, div.warning, p.warning {
   background: #f56565;
   padding: 0.1em 0.4em;
   border-radius: var(--ls-border-radius-low);

templates/tutorial-en.md

@@ -1,7 +1,7 @@
 ## Hi, welcome to Logseq!
 - Logseq is a _privacy-first_, _open-source_ platform for _knowledge_ management and collaboration.
 - This is a 3 minute tutorial on how to use Logseq. Let's get started!
-- (Feel free to edit anything, no change will be saved at this moment. If you do want to persist your work, click the **top-right** corner of the screen to connect Logseq to either Github or local directory.)
+- [:div.warning "(Feel free to edit anything, no change will be saved at this moment. If you do want to persist your work, click the **top-right** corner of the screen to either open a local directory or connect Logseq to Github.)"]
 - Here are some tips might be useful.
 #+BEGIN_TIP
 Click to edit any block.