Added custom branding steps

Signed-off-by: keithhc2 <keithhc2@users.noreply.github.com>

_dashboards/branding.md

@@ -0,0 +1,89 @@
+---
+layout: default
+title: Custom branding
+nav_order: 200
+---
+
+# Dashboards custom branding
+Introduced 1.2
+{: .label .label-purple }
+
+By default, OpenSearch Dashboards uses the OpenSearch logo, but if you want to use custom branding elements such as the favicon or main Dashboards logo, you can do so by editing `opensearch_dashboards.yml` or by including a custom `opensearch_dashboards.yml` file when you start your OpenSearch cluster.
+
+For example, if you're using Docker to start your OpenSearch cluster, include the following lines in the `opensearch-dashboards` section of your `docker-compose.yml` file:
+
+```
+volumes:
+  - ./opensearch_dashboards.yml:/usr/share/opensearch-dashboards/config/opensearch_dashboards.yml
+```
+
+Restart your OpenSearch cluster, open OpenSearch Dashboards in your browser again, and OpenSearch Dashboards now uses your custom elements.
+
+The following elements in OpenSearch Dashboards are customizable:
+
+![OpenSearch customizable branding elements]({{site.url}}{{site.baseurl}}/images/dashboards-branding-labels.png)
+
+Setting | Corresponding branding element
+:--- | :---
+logo | Header logo. See #1 in the image.
+mark | OpenSearch Dashboards mark. See #2 in the image.
+loadingLogo | Loading logo used when OpenSearch Dashboards is starting. See #3 in the image.
+faviconUrl | Website icon. Loads next to the application title. See #4 in the image.
+applicationTitle | The application's title. See #5 in the image.
+
+To start using your own branding elements in OpenSearch Dashboards, first uncomment this section of `opensearch_dashboards.yml`:
+
+```yml
+# opensearchDashboards.branding:
+  # logo:
+    # defaultUrl: ""
+    # darkModeUrl: ""
+  # mark:
+    # defaultUrl: ""
+    # darkModeUrl: ""
+  # loadingLogo:
+    # defaultUrl: ""
+    # darkModeUrl: ""
+  # faviconUrl: ""
+  # applicationTitle: ""
+```
+
+Add the URLs you want to use as branding elements to the appropriate setting. Valid image types are `SVG`, `PNG`, and `GIF`.
+
+Customization of dark mode Dashboards is also available, but you first must supply a valid link to `defaultUrl`, and then link to your preferred image with `darkModeUrl`. You are not required to customize all branding elements, so if you wanted to, it's perfectly valid to change just the logo. Leave unchanged elements as commented.
+
+The following example demonstrates how to use `SVG` files as logos but leaves the other elements as defaults.
+
+```yml
+logo:
+  defaultUrl: "https://example.com/validUrl.svg"
+  darkModeUrl: "https://example.com/validDarkModeUrl.svg"
+# mark:
+#   defaultUrl: ""
+#   darkModeUrl: ""
+# loadingLogo:
+#   defaultUrl: ""
+#   darkModeUrl: ""
+# faviconUrl: ""
+applicationTitle: "My custom application"
+```
+
+We recommend linking to images that are hosted on some web server, but if you really want to use locally hosted images, save your images inside `src/core/server/core_app/assets`, and then configure `opensearch_dashboards.yml`. You can access locally stored images through the `ui` folder.
+
+The following example assumes the default port of 5601 that Dashboards uses and demonstrates how to link to locally stored images.
+
+```yml
+logo:
+  defaultUrl: "https://localhost:5601/ui/my-own-image.svg"
+  darkModeUrl: "https://localhost:5601/ui/my-own-image.svg"
+mark:
+  defaultUrl: "https://localhost:5601/ui/my-own-image2.svg"
+  darkModeUrl: "https://localhost:5601/ui/my-own-image2.svg"
+# loadingLogo:
+#   defaultUrl: ""
+#   darkModeUrl: ""
+# faviconUrl: ""
+applicationTitle: "My custom application"
+```
+
+We don't recommend this workaround because new versions of Dashboards would revert all customized elements back to default branding elements, so you would have to re-upload your assets to access them again.