0860 form history: add setup tag / warning

- Used setup-web since it relates to actual web pages, even though it doesn't break them
- Added the tag because it's an item that is likely to get attention / troubleshooting
- Added a warning tag to make the risk more apparent.
- Slight edit to the 2803 references

user.js

@@ -601,14 +601,14 @@ user_pref("browser.urlbar.speculativeConnect.enabled", false);
 /* 0850e: disable location bar one-off searches [FF51+]
  * [1] https://www.ghacks.net/2016/08/09/firefox-one-off-searches-address-bar/ ***/
    // user_pref("browser.urlbar.oneOffSearches", false);
-/* 0860: disable search and form history
- * Autocomplete form data is still (in April 2019) easily read by third parties, see [1]
- * [NOTE] You can clear formdata on exiting Firefox (see 2803)
+/* 0860: disable search and form history [SETUP-WEB]
+ * [WARNING] Autocomplete form data is still (in April 2019) easily read by third parties, see [1]
+ * [NOTE] We also clear formdata on exiting Firefox (see 2803)
  * [SETTING] Privacy & Security>History>Custom Settings>Remember search and form history
  * [1] https://blog.mindedsecurity.com/2011/10/autocompleteagain.html ***/
 user_pref("browser.formfill.enable", false);
 /* 0862: disable browsing and download history
- * [NOTE] You can clear history and downloads on exiting Firefox (see 2803)
+ * [NOTE] We also clear history and downloads on exiting Firefox (see 2803)
  * [SETTING] Privacy & Security>History>Custom Settings>Remember browsing and download history ***/
    // user_pref("places.history.enabled", false);
 /* 0864: disable date/time picker