Fixed broken links (KhronosGroup#163)

Fixed broken links in README and sample tutorials.

Fixes KhronosGroup#161

README.md

@@ -69,13 +69,13 @@ Additionally you may find the following links useful:
 - **Descriptors**
   - [Descriptor and buffer management](./samples/performance/descriptor_management/descriptor_management_tutorial.md)
 - **Constant Data**
-  - [Sending constant data to the shaders](./samples/performance/constant_data/)
+  - [Sending constant data to the shaders](./samples/performance/constant_data/constant_data_tutorial.md)
 - **Render Passes**
   - [Appropriate use of load/store operations, and use of transient attachments](./samples/performance/render_passes/render_passes_tutorial.md)
   - [Choosing the correct layout when transitioning images](./samples/performance/layout_transitions/layout_transitions_tutorial.md)
   - [How to implement MSAA](./samples/performance/msaa/msaa_tutorial.md)
 - **Render Subpasses**
-  - [Benefits of subpasses over multiple render passes, use of transient attachments, and G-buffer recommended size](./samples/performance/render_subpasses/render_subpasses_tutorial.md)
+  - [Benefits of subpasses over multiple render passes, use of transient attachments, and G-buffer recommended size](./samples/performance/subpasses/subpasses_tutorial.md)
 - **Workload Synchronization**
   - [Using pipeline barriers efficiently](./samples/performance/pipeline_barriers/pipeline_barriers_tutorial.md)
   - [How to synchronize back to the CPU and avoid stalling](./samples/performance/wait_idle/wait_idle_tutorial.md)

samples/performance/descriptor_management/descriptor_management_tutorial.md

@@ -1,5 +1,5 @@
 <!--
-- Copyright (c) 2019, Arm Limited and Contributors
+- Copyright (c) 2019-2020, Arm Limited and Contributors
 -
 - SPDX-License-Identifier: Apache-2.0
 -
@@ -72,7 +72,7 @@ This system is reasonably easy to implement for a static scene, but it becomes h
 This may correspond to calling [vkFreeDescriptorSets()](https://www.khronos.org/registry/vulkan/specs/1.1-extensions/man/html/vkFreeDescriptorSets.html), but this solution poses another issue: in order to free individual descriptor sets the pool has to be created with the `VK_DESCRIPTOR_POOL_CREATE_FREE_DESCRIPTOR_SET_BIT` flag.
 Mobile implementations may use a simpler allocator if that flag is not set, relying on the fact that pool memory will only be recycled in block.
 
-It is possible to avoid using that flag by updating descriptor sets instead of deleting them. The application can keep track of recycled descriptor sets and re-use one of them when a new one is requested. The [render subpasses sample](../render_subpasses/render_subpasses_tutorial.md) uses this approach when it re-creates the G-buffer images.
+It is possible to avoid using that flag by updating descriptor sets instead of deleting them. The application can keep track of recycled descriptor sets and re-use one of them when a new one is requested. The [subpasses sample](../subpasses/subpasses_tutorial.md) uses this approach when it re-creates the G-buffer images.
 
 ## Buffer management
 

samples/performance/layout_transitions/layout_transitions_tutorial.md

@@ -78,7 +78,7 @@ The sample sets up deferred rendering using two render passes, to show the effec
 G-buffer images from `UNDEFINED` rather than their last known layout.
 
 Note that a deferred rendering implementation using subpasses might be more efficient overall;
-see [the subpasses tutorial](../render_subpasses/render_subpasses_tutorial.md) for more detail.
+see [the subpasses tutorial](../subpasses/subpasses_tutorial.md) for more detail.
 
 The base case is with all color images being transitioned from `UNDEFINED`, as shown in the image below.
 

samples/performance/pipeline_barriers/pipeline_barriers_tutorial.md

@@ -115,7 +115,7 @@ The app is fragment-bound, which allows the GPU to fully utilize pipelining.
 The sample sets up deferred rendering with two render passes and uses pipeline barriers to
 synchronize them.
 Note that a deferred rendering implementation using subpasses might be more efficient overall;
-see [the subpasses tutorial](../render_subpasses/render_subpasses_tutorial.md) for more detail.
+see [the subpasses tutorial](../subpasses/subpasses_tutorial.md) for more detail.
 
 The base case is with the most conservative barrier (`BOTTOM_OF_PIPE_BIT` → `TOP_OF_PIPE_BIT`).
 As the graphs show, vertex and fragment work are serialized, as they never happen at the same time.