Escapehtmlinheadertitle

Expected Behaviour

When adding a html tags to H1's in markdown files, such as Font awesome icons, the html title should strip the html and therefore display the title text only

Current Behaviour

Adding html to H1's in markdown files is displayed unescaped in the title

Possible Solution

Stripping all html when reading the property in as a Jinja template. This PR addresses the issue in this way.

Steps to Reproduce

1. Add
   

   1	fontawesome_markdown

   extension and

   1	awesome-pages

   plugin



2. Add Font Awseome icon to any .md file


3. Navigate to the page you have edited


4. The page title, also displayed as the tab title, contains the unescaped html

该提问来源于开源项目：squidfunk/mkdocs-material