web/about: revise text on all pages & improve readability

all information is way easier to read and understand. i also added info about new features and explained some concepts in a better language.

web/i18n/en/about.json

@@ -11,9 +11,9 @@
     "heading.general": "general terms",
     "heading.licenses": "licenses",
     "heading.summary": "best way to save what you love",
-    "heading.privacy": "leading privacy",
+    "heading.privacy_efficiency": "leading privacy & efficiency",
     "heading.community": "open community",
-    "heading.local": "on-device processing",
+    "heading.local": "local processing",
     "heading.saving": "saving",
     "heading.encryption": "encryption",
     "heading.plausible": "anonymous traffic analytics",
@@ -22,6 +22,7 @@
     "heading.abuse": "reporting abuse",
     "heading.motivation": "motivation",
     "heading.testers": "beta testers",
+    "heading.partners": "partners",
 
     "support.github": "check out cobalt's source code, contribute changes, or report issues",
     "support.discord": "chat with the community and developers about cobalt or ask for help",