Fixed broken links in readthedocs

Added releases.md and AttributesUsage API.md in mkdocs.yml file
also fixed broken links in index.md [ci skip]

Change-Id: I3650114d416aaffb8b3669353c7a6abd68ec9c9f
Signed-off-by: rameshbabu79 <[email protected]>

Author: rameshthoomu

docs/index.md

@@ -27,7 +27,7 @@ v0.6-preview.
 
 If you'd like to dive right in and get an operational experience on your local
 server or laptop to begin development, we have just the thing for you. We have
-created a standalone Docker-based [starter kit](Starter/fabric-starter-kit.md)
+created a standalone Docker-based [starter kit](starter/fabric-starter-kit.md)
 that leverages the latest published Docker images that you can run on your
 laptop and be up and running in no time. That should get you going with a
 sample application and some simple chaincode. From there, you can go deeper

mkdocs.yml

@@ -13,7 +13,9 @@ pages:
 - Protocol Spec: protocol-spec.md
 - Usecases: biz/usecases.md
 
-- Release Notes: v0.6_migration.md
+- Release Notes:
+  - Migration Considerations: v0.6_migration.md
+  - Releases: releases.md
 
 - Starter Kit:
   - Starter Kit: starter/fabric-starter-kit.md
@@ -31,7 +33,8 @@ pages:
   - Chaincode APIs: API/ChaincodeAPI.md
   - Core API: API/CoreAPI.md
   - CA API: API/MemberServicesAPI.md
-  - System Chaincode: SystemChaincodes/noop.md
+  - AttributesUsage API: API/AttributesUsage.md
+  - System Chaincode: SystemChaincode-noop.md
 
 - Fabric Developer:
   - v1.0 Preview: abstract_v1.md