Update Salesforce Outbound provisioning docs with User Fields info

[asha15]

In advance claims configuration we asked users to provide default values ​​for claims URIs, but we did not specify the number of characters allowed for claims in the Salesforce form. So if a user has configured a claim with more than the number of characters allowed, provisioning may not work as expected.

Related Docs:

• https://is.docs.wso2.com/en/latest/learn/outbound-provisioning-with-salesforce
• https://is.docs.wso2.com/en/latest/learn/configuring-outbound-provisioning
• https://help.salesforce.com/s/articleView?id=sf.user_fields.htm&type=5