Add markdown support to post body

Implemented markdown support in the post body to enhance the
editor's functionality. The main blog view now renders markdown
content as HTML. This change allows users to format their posts
using markdown syntax, providing a richer text editing experience.

- Imported the markdown module in blog.py.
- Converted post bodies from markdown to HTML in the index view.
- Updated templates to indicate markdown support in the post body
  field.
- Ensured safe rendering of HTML content in the blog index view.

Fixes #FLAS-29

flaskr/blog.py

@@ -6,6 +6,7 @@ from flask import render_template
 from flask import request
 from flask import url_for
 from werkzeug.exceptions import abort
+import markdown
 
 from .auth import login_required
 from .db import get_db
@@ -22,6 +23,9 @@ def index():
         " FROM post p JOIN user u ON p.author_id = u.id"
         " ORDER BY created DESC"
     ).fetchall()
+    # Convert markdown to HTML for each post body
+    for post in posts:
+        post['body'] = markdown.markdown(post['body'])
     return render_template("blog/index.html", posts=posts)