[FAB-12371]Fix the doc to use new cid package

The latest cid package is fabric/core/chaincode/shim/ext/cid.
This CR fixes the doc to use the new cid package instead of the
old one at fabric/core/chaincode/lib/cid.

Change-Id: Ie7b9cba186eb7cd5ec08f83b1578466f499b8bd9
Signed-off-by: Yuki Kondo <yuki.kondo@hal.hitachi.com>

core/chaincode/shim/ext/cid/README.md

@@ -23,7 +23,7 @@ All code samples below assume two things:
  to your chaincode.
 2. You have added the following import statement to your chaincode.
  ```
- import "github.com/hyperledger/fabric/core/chaincode/lib/cid"
+ import "github.com/hyperledger/fabric/core/chaincode/shim/ext/cid"
  ```
 #### Getting the client's ID
 

docs/source/chaincode4ade.rst

@@ -35,7 +35,7 @@ Chaincode API
  such access control decisions.
 
  We won't cover that in this tutorial, however it is
- `documented here <https://github.com/hyperledger/fabric/blob/master/core/chaincode/lib/cid/README.md>`_.
+ `documented here <https://github.com/hyperledger/fabric/blob/master/core/chaincode/shim/ext/cid/README.md>`_.
 
 Every chaincode program must implement the ``Chaincode`` interface:
 

docs/source/private-data-arch.rst

@@ -204,7 +204,7 @@ Limitations:
  non-authorized clients are able to invoke chaincode on peers that have access
  to the private data, the chaincode logic still needs a means to enforce access
  control as usual, for example by calling the GetCreator() chaincode API or
- using the client identity `chaincode library <https://github.com/hyperledger/fabric/tree/master/core/chaincode/lib/cid>`__ .
+ using the client identity `chaincode library <https://github.com/hyperledger/fabric/tree/master/core/chaincode/shim/ext/cid>`__ .
 
 Using Indexes with collections
 ------------------------------