[add] Product page link to the docs footer

- new "Product page" item in the Development center column, after Download Spreadsheet
- links to https://dhtmlx.com/docs/products/dhtmlxSpreadsheet/
- translated label for de, ko, ru, zh footers

Author: mafanya23

docusaurus.config.js

@@ -266,6 +266,11 @@ module.exports = {
                             href: 'https://dhtmlx.com/docs/products/dhtmlxSpreadsheet/download.shtml',
                             position: 'right'
                         },
+                        {
+                            label: 'Product page',
+                            href: 'https://dhtmlx.com/docs/products/dhtmlxSpreadsheet/',
+                            position: 'right'
+                        },
                         {
                             label: 'Examples',
                             href: 'https://snippet.dhtmlx.com/ihtkdcoc?tag=spreadsheet',

i18n/de/docusaurus-theme-classic/footer.json

@@ -15,6 +15,10 @@
     "message": "Spreadsheet herunterladen",
     "description": "The label of footer link with label=Download Spreadsheet linking to https://dhtmlx.com/docs/products/dhtmlxSpreadsheet/download.shtml"
   },
+  "link.item.label.Product page": {
+    "message": "Produktseite",
+    "description": "The label of footer link with label=Product page linking to https://dhtmlx.com/docs/products/dhtmlxSpreadsheet/"
+  },
   "link.item.label.Examples": {
     "message": "Beispiele",
     "description": "The label of footer link with label=Examples linking to https://snippet.dhtmlx.com/ihtkdcoc?tag=spreadsheet"

i18n/ko/docusaurus-theme-classic/footer.json

@@ -15,6 +15,10 @@
     "message": "Spreadsheet 다운로드",
     "description": "The label of footer link with label=Download Spreadsheet linking to https://dhtmlx.com/docs/products/dhtmlxSpreadsheet/download.shtml"
   },
+  "link.item.label.Product page": {
+    "message": "제품 페이지",
+    "description": "The label of footer link with label=Product page linking to https://dhtmlx.com/docs/products/dhtmlxSpreadsheet/"
+  },
   "link.item.label.Examples": {
     "message": "예제",
     "description": "The label of footer link with label=Examples linking to https://snippet.dhtmlx.com/ihtkdcoc?tag=spreadsheet"

i18n/ru/docusaurus-theme-classic/footer.json

@@ -15,6 +15,10 @@
     "message": "Скачать Spreadsheet",
     "description": "The label of footer link with label=Download Spreadsheet linking to https://dhtmlx.com/docs/products/dhtmlxSpreadsheet/download.shtml"
   },
+  "link.item.label.Product page": {
+    "message": "Страница продукта",
+    "description": "The label of footer link with label=Product page linking to https://dhtmlx.com/docs/products/dhtmlxSpreadsheet/"
+  },
   "link.item.label.Examples": {
     "message": "Примеры",
     "description": "The label of footer link with label=Examples linking to https://snippet.dhtmlx.com/ihtkdcoc?tag=spreadsheet"

i18n/zh/docusaurus-theme-classic/footer.json

@@ -15,6 +15,10 @@
     "message": "下载 Spreadsheet",
     "description": "The label of footer link with label=Download Spreadsheet linking to https://dhtmlx.com/docs/products/dhtmlxSpreadsheet/download.shtml"
   },
+  "link.item.label.Product page": {
+    "message": "产品页面",
+    "description": "The label of footer link with label=Product page linking to https://dhtmlx.com/docs/products/dhtmlxSpreadsheet/"
+  },
   "link.item.label.Examples": {
     "message": "示例",
     "description": "The label of footer link with label=Examples linking to https://snippet.dhtmlx.com/ihtkdcoc?tag=spreadsheet"