Standardize search/find to search (#7398)

* Change 'Find a file' to 'File search' for consistency

There is 'File search' in the Gesture manager already.
There is 'Fulltext search' in the readermenu.
Some help text added.

frontend/apps/reader/modules/readerwikipedia.lua

@@ -37,7 +37,7 @@ end
 
 function ReaderWikipedia:lookupInput()
     self.input_dialog = InputDialog:new{
-        title = _("Enter words to look up on Wikipedia"),
+        title = _("Enter a word or phrase to look up"),
         input = "",
         input_type = "text",
         buttons = {
@@ -249,7 +249,7 @@ function ReaderWikipedia:addToMainMenu(menu_items)
                             local text = _([[
 Wikipedia articles can be saved as an EPUB for more comfortable reading.
 
-You can select an existing directory, or use a default directory named "Wikipedia" in your reader's home folder.
+You can select an existing folder, or use a default folder named "Wikipedia" in your reader's home folder.
 
 Where do you want them saved?]])
                             UIManager:show(ConfirmBox:new{
@@ -442,7 +442,7 @@ function ReaderWikipedia:lookupWikipedia(word, is_sane, box, get_fullpage, force
     else
         self.lookup_msg = T(_("Searching Wikipedia %2 for:\n%1"), "%1", lang:upper())
         req_failure_text = _("Failed searching Wikipedia.")
-        no_result_text = _("No Wikipedia articles matching search term.")
+        no_result_text = _("No results.")
     end
     self:showLookupInfo(display_word)