[CrOS Settings] Fix learn more link on nearby printers learn more link.

In https://chromium-review.googlesource.com/c/chromium/src/+/1967803,
while learn more links were being swapped out with
settings-localized-link elements, "nearbyPrintersListDescription" was
incorrectly used for the link-url attribute when
"printingCUPSPrintLearnMoreUrl" should have been instead.  This CL
corrects that mistake.

Fixed: 1038646
Change-Id: If35351143c81c17e2bcaec0268281a41d9fcf576
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1985137Reviewed-by: Dan Beam <dbeam@chromium.org>
Commit-Queue: Regan Hsu <hsuregan@chromium.org>
Auto-Submit: Regan Hsu <hsuregan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#728225}

chrome/browser/resources/settings/chromeos/os_printing_page/cups_printers.html

@@ -153,7 +153,7 @@
         </div>
         <settings-localized-link class="secondary"
             localized-string="$i18n{nearbyPrintersListDescription}"
-            link-url="$i18n{nearbyPrintersListDescription}">
+            link-url="$i18n{printingCUPSPrintLearnMoreUrl}">
         </settings-localized-link>
         <template is="dom-if" if="[[!addPrinterButtonActive_(canAddPrinter,
             prefs.native_printing.user_native_printers_allowed.value)]]">