Update PECE changelog.

CHANGELOG_PECE.txt

@@ -1,3 +1,15 @@
+* PECE v1.34 (05/12/2021)
+
+Security Updates,  User Interface updates, New features and improvements on citation standards - Archival Resource Key (ARK), Digital Object Identifiers (DOI).  
+
+- Upgrade Drupal core to v7.80
+- Create Zenodo file with updated information for citation
+- Allow site administrator to choose which content to have ARK identifiers
+- Add 'Cite as' box on content page 
+- Add navigation arrows on Home page slider
+- Add Project ref. on Artifacts and Essays
+
+
 * PECE v1.33 (01/25/2021)
 
 Security Update, bug fixes and content permission update.