Add Mermaid.js icon (#9808)

_data/simple-icons.json

@@ -8174,6 +8174,11 @@
                 "type": "GPL-2.0-or-later"
             }
         },
+        {
+            "title": "Mermaid",
+            "hex": "FF3670",
+            "source": "https://github.com/mermaid-js/mermaid/blob/f5bd1e08098fa688ef889e73c8b06696e75e62d8/docs/public/mermaid-logo.svg"
+        },
         {
             "title": "Messenger",
             "hex": "00B2FF",

icons/mermaid.svg

@@ -0,0 +1 @@
+<svg role="img" viewBox="0 0 24 24" xmlns="http://www.w3.org/2000/svg"><title>Mermaid</title><path d="M23.99 2.115A12.223 12.223 0 0 0 12 10.149 12.223 12.223 0 0 0 .01 2.115a12.23 12.23 0 0 0 5.32 10.604 6.562 6.562 0 0 1 2.845 5.423v3.754h7.65v-3.754a6.561 6.561 0 0 1 2.844-5.423 12.223 12.223 0 0 0 5.32-10.604Z"/></svg>