Add once-useful lua script

Signed-off-by: Danila Fedorin <danila.fedorin@gmail.com>

content/blog/music_theory/svg-inline.lua

@@ -0,0 +1,13 @@
+function Image(el)
+  local src = el.src
+  if src:match("%.svg$") then
+    local alt = el.caption and pandoc.utils.stringify(el.caption) or ""
+    local obj = string.format(
+      '{{< inlinesvg "%s" "%s" >}}',
+      src, alt
+    )
+    return pandoc.RawInline("html", obj)
+  else
+    return el
+  end
+end