Schema Registry readme and samples issues

[AFengKK]

Section link1, link2:

Reason 1:
The order of the parameters is wrong.
Reason 2:
AttributeError: 'SchemaProperties' object has no attribute 'schema_id'.

Suggestion 1:
Update to schema_content, serialization_type
Suggestion 2:
Update to id

Section link1, link2, link3:

Reason :
TypeError: init() missing 1 required positional argument: 'fully_qualified_namespace'.

Suggestion :
Update to fully_qualified_namespace

Section link:

Reason :
AttributeError: 'Schema' object has no attribute 'content'.

Suggestion :
Update to schema_definition

Section link:

Reason :
AttributeError: 'SchemaRegistryClient' object has no attribute 'get_schema_id'.

Suggestion :
Update to get_schema_properties

Section link1, link2, link3, link4:

Reason:
TypeError: init() takes 1 positional argument but 3 were given.

Suggestion:
Update to client=schema_registry_client, group_name=schema_group

Section link1, link2:

Reason 1:
TypeError: serialize() takes 2 positional arguments but 3 were given.
Reason 2:
TypeError: serialize() missing 1 required positional argument: 'value'.

Suggestion 1,2:
Update to value=dict_data, schema=schema_string

@jameszliao-msft , @lmazuel , @ramya-rao-a , @yunhaoling for notification.

[swathipil]

@AFengKK - thanks for your thorough description! PR with fixes will be going out soon.