Use markdown for the badge so it gets picked up by the site

Author: abelsiqueira

src/JSOTutorials.jl

@@ -106,10 +106,10 @@ function badge(name, version)
     "000", "fff"
   end
 
-  badge_img = "<img class=\"badge\" src=\"https://img.shields.io/badge/$name-$version-$color?style=flat-square&labelColor=$lbl_color\">"
+  badge_img = "![$name $version](https://img.shields.io/badge/$name-$version-$color?style=flat-square&labelColor=$lbl_color\")"
   if name in jso_pkgs
     link = "https://juliasmoothoptimizers.github.io/$name.jl/stable/"
-    "<a href=\"$link\">$badge_img</a>"
+    "[$badge_img]($link)"
   else
     badge_img
   end

tutorials/introduction-to-linear-operators/index.jmd

@@ -4,8 +4,7 @@ tags: ["linear-algebra", "linear-operators"]
 author: "Geoffroy Leconte and Dominique Orban"
 ---
 
-[LinearOperators.jl](https://juliasmoothoptimizers.github.io/LinearOperators.jl/stable) is a package for matrix-like operators.
-Linear operators are defined by how they act on a vector, which is useful in a variety of situations where you don't want to materialize the matrix.
+[LinearOperators.jl](https://juliasmoothoptimizers.github.io/LinearOperators.jl/stable) is a package for matrix-like operators. Linear operators are defined by how they act on a vector, which is useful in a variety of situations where you don't want to materialize the matrix.
 
 \toc