Planetary bits

Just a few minor additions plus a few typos etc.

data/contact.yaml

@@ -57,6 +57,13 @@ people: [
     affil: "ICC, Durham University",
   },
   {
+    name: Mr. Jacob Kegerreis,
+    role: PhD Student (astronomy),
+    affil: "ICC, Durham University",
+    expertise: "Planetary giant impacts",
+    href: "https://www.dur.ac.uk/physics/staff/profiles/?username=cklv53"
+  },
+  {
     name: Mr. Joshua Borrow,
     role: PhD Student (astronomy),
     href: "http://www.dur.ac.uk/joshua.borrow",