Update section titles for alumni categories

Author: Jina-Kim

people.html

@@ -101,7 +101,7 @@ <h3>{{member.name}}</h3>
 </div>
 <div class='full'>
   <div class='row'>
-    <h2> PhD Alumni </h2>
+    <h2> Ph.D. Alumni </h2>
       {% for member in site.data.people.phd-alumni %}
             <div class='modPeople'>
               {% if member.link %}
@@ -119,7 +119,7 @@ <h3>{{member.name}}</h3>
 </div>
 <div class='full'>
   <div class='row'>
-    <h2> Alumni </h2>
+    <h2> Other Alumni </h2>
       {% for member in site.data.people.alumni %}
             <div class='modPeople'>
               {% if member.link %}