[iOS] Doc config Apple App Id to support universal links

[nasli]

1. The app IDs must be enabled the Associated Domains

Editing App IDs
You can edit an App ID directly using your developer account.
To enable app services for an existing App ID
Sign in to developer.apple.com/account, and click Certificates, IDs & Profiles.
Under Identifiers, select App IDs.
Select the App ID you want to change, and click Edit.
Select the corresponding checkboxes to enable the app service associated Domains.

2. Inside the app we need to enable associated domains with the links supported ( We need to update jenkins script to dynamically update it using the correct bundle id)

Configuring Associated Domains (iOS)
In the Capabilities pane, if Associated Domains isn’t enabled, click the switch in the Associated Domains section.
Click the Add button (+) at the bottom of the Domains table.
Double-click the placeholder text in the table, and enter the domain name you want to add.

Related
owncloud/enterprise#2173

owncloud/ios-legacy#972

https://github.com/owncloud/branded_clients/blob/cd99beb054fbd8bef9e30948cf75e046cfdc9cd6/branded_ios_app/publishing_ios_app_8.rst

[SamuAlfageme]

Also notice that, if there's multiple URLs (e.g. internal/external domains; proxies, etc) to access an instance with this feature, an explicit listing of those is required.

To do this in Xcode, open the Associated Domains section in the Capabilities tab and add an entry for each domain that your app supports, prefixed with applinks:, such as applinks:www.mywebsite.com. Limit this list to no more than about 20 to 30 domains.

ref. https://github.com/owncloud/ownbrander/issues/769