doc: clean up unused session link

Remove the "VimTeX on the web" section link from README.md, as its content was previously deleted in commit 1b4df78. This helps clean up dead anchors in the document and avoids confusion for users browsing the README.

Author: Sphaela

README.md

@@ -27,7 +27,6 @@ filetype and syntax plugin for LaTeX files.
   - [Snippets and templates](#snippets-and-templates)
   - [Tag navigation](#tag-navigation)
 - [Alternatives](#alternatives)
-- [VimTeX on the Web](#vimtex-on-the-web)
 
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