Add contact page

bin/build/annotated.awk

@@ -11,6 +11,7 @@ BEGIN {
     print "path: /annotated-spec"
     print "titles: [\"One Page Annotated Spec\",\"\",\"\"]"
     print "index: [999]"
+    print "sequence: 990"
     print "---"
 }
 

src/md/contact.md

@@ -0,0 +1,13 @@
+---
+path: /contact
+titles: ["Contact me","",""]
+index: [999]
+sequence: 999
+---
+# Contact me
+
+Feel free to [DM me on Twitter](https://twitter.com/benjaminion_xyz/) with any feedback.
+
+For typos, corrections, omissions and the like please either drop me a line as above, or raise a [GitHub issue](https://github.com/benjaminion/upgrading-ethereum-book/issues). I'd rather you didn't make a PR as it's easier to fix things in my upstream repo than to backport fixes.
+
+Looking forward to hearing from you 🙂