.azurepipelines: Update pipeline filenames

Details about a particular pipeline change over time - such as the
specific Linux distro or toolchain version. At the same time, the
pipeline files are directly referenced in Azure Pipelines to run the
pipeline and few users have access to change those details.

To make the files less likely to refer to outdated information over
time and reduce the need for an Azure Pipeline administrator to get
involved, the files are updated to drop specific details apart from
the host OS environment used in the pipeline.

Signed-off-by: Michael Kubacki <michael.kubacki@microsoft.com>

.azurepipelines/ReadMe.md

@@ -19,7 +19,10 @@ Focused on building a single target platform and confirming functionality on tha
 * Platform CI files should be in the `<PlatformPkg>/.azurepipelines` folder.
 * Core CI files are in the root folder.
 * Shared templates are in the `templates` folder.
-* Top level CI files should be named `<host os>-<tool_chain_tag>.yml`
+* Top level CI files should be named `<host os>-<tool_chain>.yml`
+  * The pipeline YAML file name is referenced in Azure Pipelines. To allow flexibility for toolchain updates in the
+    YAML file without necessitating changes in Azure Pipelines, the toolchain version is not included in the filename.
+    For example, `Windows-VS.yml` is used instead of `Windows-VS2022.yml`.
 
 ## Links
 

.azurepipelines/Ubuntu-GCC.yml

@@ -1,5 +1,5 @@
 ## @file
-# Azure Pipeline build file for a build using ubuntu and GCC5
+# Azure Pipeline build file for a build using Ubuntu and GCC
 #
 # Copyright (c) Microsoft Corporation.
 # Copyright (c) 2020, Hewlett Packard Enterprise Development LP. All rights reserved.<BR>

.azurepipelines/Windows-VS.yml

@@ -1,5 +1,5 @@
 ## @file
-# Azure Pipeline build file for a build using Windows and VS2022
+# Azure Pipeline build file for a build using Windows and Visual Studio
 #
 # Copyright (c) Microsoft Corporation.
 # SPDX-License-Identifier: BSD-2-Clause-Patent