i18n: add TRANSLATORS comment to Validate nav item in LeftSidebar

Signed-off-by: Vitor Mattos <1079143+vitormattos@users.noreply.github.com>

Author: vitormattos

src/components/LeftSidebar/LeftSidebar.vue

@@ -23,6 +23,7 @@
 					<NcIconSvgWrapper :path="mdiFolder" :size="20" />
 				</template>
 			</NcAppNavigationItem>
+			<!-- TRANSLATORS: Navigation menu item. "Validate" here is a technical process: the app checks the cryptographic integrity of a document's signatures, the certificate chain and revocation status. It does NOT mean approving or authorizing something. Choose a word in your language that conveys "to check" or "to verify", not "to approve" or "to authorize". -->
 			<NcAppNavigationItem id="validation"
 				:to="{name: 'validation'}"
 				:name="t('libresign', 'Validate')"