Fix typo in Open Graph description for docs (#6641)

docs/index.html

@@ -8,7 +8,7 @@
   <meta name="viewport" content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">  
   <meta property="og:title" content="QMK Firmware Docs">
   <meta property="og:type" content="website">
-  <meta property="og:description" content="The full documenation of the open-source firmware">
+  <meta property="og:description" content="The full documentation of the open-source firmware">
   <meta property="og:image" content="https://i.imgur.com/svjvIrw.jpg">
   <meta property="og:url" content="https://docs.qmk.fm">
   <meta name="twitter:card" content="summary_large_image">