docs: Update API documentations for Beta Program (#355)

Author: yec-akamai

linode_api4/groups/account.py

@@ -457,7 +457,7 @@ def enrolled_betas(self, *filters):
         """
         Returns a list of all Beta Programs an account is enrolled in.
 
-        API doc: TBD
+        API doc: https://www.linode.com/docs/api/beta-programs/#enrolled-beta-programs-list
 
         :returns: a list of Beta Programs.
         :rtype: PaginatedList of AccountBetaProgram
@@ -468,7 +468,7 @@ def join_beta_program(self, beta: Union[str, BetaProgram]):
         """
         Enrolls an account into a beta program.
 
-        API doc: TBD
+        API doc: https://www.linode.com/docs/api/beta-programs/#beta-program-enroll
 
         :param beta: The object or id of a beta program to join.
         :type beta: BetaProgram or str

linode_api4/groups/beta.py

@@ -12,7 +12,7 @@ def betas(self, *filters):
         """
         Returns a list of available active Beta Programs.
 
-        API Documentation: TBD
+        API Documentation: https://www.linode.com/docs/api/beta-programs/#beta-programs-list
 
         :param filters: Any number of filters to apply to this query.
                         See :doc:`Filtering Collections</linode_api4/objects/filtering>`

linode_api4/objects/account.py

@@ -642,6 +642,8 @@ def save(self):
 class AccountBetaProgram(Base):
     """
     The details and enrollment information of a Beta program that an account is enrolled in.
+
+    API Documentation: https://www.linode.com/docs/api/beta-programs/#enrolled-beta-program-view
     """
 
     api_endpoint = "/account/betas/{id}"

linode_api4/objects/beta.py

@@ -6,7 +6,7 @@ class BetaProgram(Base):
     Beta program is a new product or service that's not generally available to all customers.
     User with permissions can enroll into a beta program and access the functionalities.
 
-    API Documentation: TBD
+    API Documentation: https://www.linode.com/docs/api/beta-programs/#beta-program-view
     """
 
     api_endpoint = "/betas/{id}"