docs: fix minor one/on typo (remy#4)

si · remy · commit 5f4cb4c9094e · 2019-06-20T18:20:44.000+01:00
diff --git a/pages/about.vue b/pages/about.vue
@@ -3,7 +3,7 @@
 
 [Remy Sharp](https://remysharp.com) wrote webmention.app because it seemed like webmention notification systems were thin on the ground, and wanted to use a notification system that was agnostic of the user software.
 
-The service is currently free, and will remain so, as it is able to run one a single server with little to zero maintenance.
+The service is currently free, and will remain so, as it is able to run on a single server with little to zero maintenance.
 
 If you want to contact there's a few ways:
 
