src/assets/i18n/en.json5: minor updates for consistency

We should be capitalizing acronyms and project-specific nouns like
MyDSpace consistently in our interface.

Author: alanorth

src/assets/i18n/en.json5

@@ -590,9 +590,9 @@
 
   "admin.metadata-import.page.error.addFile": "Select file first!",
 
-  "admin.metadata-import.page.error.addFileUrl": "Insert file url first!",
+  "admin.metadata-import.page.error.addFileUrl": "Insert file URL first!",
 
-  "admin.batch-import.page.error.addFile": "Select Zip file first!",
+  "admin.batch-import.page.error.addFile": "Select ZIP file first!",
 
   "admin.metadata-import.page.toggle.upload": "Upload",
 
@@ -3028,9 +3028,9 @@
 
   "mydspace.results.no-title": "No title",
 
-  "mydspace.results.no-uri": "No Uri",
+  "mydspace.results.no-uri": "No URI",
 
-  "mydspace.search-form.placeholder": "Search in mydspace...",
+  "mydspace.search-form.placeholder": "Search in MyDSpace...",
 
   "mydspace.show.workflow": "Workflow tasks",