[MINOR] Updating contributors

Updating contributors list, adding new PPMC members and fixing a typo.

Author: Marco Gaido <marcogaido91@gmail.com>

Closes #25 from mgaido91/contrib.
diff --git a/site/_data/contributors.yml b/site/_data/contributors.yml
index 7b9c26b..7dbe984 100644
--- a/site/_data/contributors.yml
+++ b/site/_data/contributors.yml
@@ -21,14 +21,14 @@
 - name: Alex Bozarth
   apacheId: ajbozarth
   githubId: ajbozarth
-  role: Committer
+  role: PMC
   org: IBM
 
 - name: Alex Man
   apacheId:
   githubId: alex-the-man
   role: PMC
-  org: Independant
+  org: Independent
 
 - name: Bikas Saha
   apacheId: bikas
@@ -72,6 +72,12 @@
   role: PMC
   org: Cloudera
 
+- name: Marco Gaido
+  apacheId: mgaido
+  githubId: mgaido91
+  role: PMC
+  org: Independent
+
 - name: Saisai Shao
   apacheId: jshao
   githubId: jerryshao