fixing spelling issue

Author: TomJaeger

docs/toc_sections/_advanced_usage_toc.yml

@@ -69,7 +69,7 @@
           href: add-ons/pro-search/examples.md
         - name: Find and Replace
           href: add-ons/pro-search/find-and-replace.md
-        - name: Upgrde from Low Search
+        - name: Upgrade from Low Search
           href: add-ons/pro-search/upgrade-from-low-search.md		  
         - name: Development
           items:
@@ -97,7 +97,7 @@
           href: add-ons/pro-variables/tags.md
         - name: Fieldtype
           href: add-ons/pro-variables/fieldtype.md
-        - name: Upgrde from Low Variables
+        - name: Upgrade from Low Variables
           href: add-ons/pro-variables/upgrade-from-low-variables.md		  
         - name: Development
           items: