created ImageSubtitle element; added content to blog post 1

src/lib/image-subtitle.svelte

@@ -0,0 +1,21 @@
+<script lang="ts">
+    let {
+        content
+    }: {
+        content: string;
+    } = $props();
+</script>
+
+<span class="image-subtitle">{content}</span>
+
+<style>
+    .image-subtitle::before {
+        content: "↳ ";
+    }
+    .image-subtitle {
+        display: block;
+        width: 80%;
+        margin: 0 auto;
+        font-size: 1rem;
+    }
+</style>