[docsy] Add metadata examples, and other copyedits (#82)

Author: chalin

assets/scss/_styles_project.scss

@@ -37,3 +37,7 @@
     }
   }
 }
+
+.td-breadcrumbs__single {
+  display: none;
+}

content/en/docs/contributing.md

@@ -1,6 +1,6 @@
 ---
 title: Contributing
-weight: 700
+weight: 500
 ---
 
 Thank you for considering contributing to in-toto.io! Here are the steps to set

content/en/docs/examples/_index.md

@@ -0,0 +1,16 @@
+---
+title: Metadata examples
+aliases: [/metadata-examples]
+weight: 80
+---
+
+- [Debian](debian/) — This demo metadata shows how the Debian project could use
+  in-toto to secure their version of the grep package.
+- [Seattle](seattle/) — Seattle is a fog computing platform that already ships
+  in-toto metadata with their releases. Here, you can see a pretty-printed
+  version of the seattle metadata.
+- [PPH](polypasswordhasher/) — [PolyPasswordHasher](https://pph.io/) is a
+  password hashing scheme that prevents an attacker from cracking passwords
+  individually and efficiently.
+
+Don't forget to check out our [demos](https://github.com/in-toto/demo) too.