Fix broken links in gflags.md

Removes broken links to the `global-flag-reference.md` file, which doesn't seem to exist in this repo.

Fixes link to GFlags examples, there is no "index" page with links to all of the examples, so instead just link to the first one in the list.

Corrects the name of the `Administrators` group, this is not possessive

Author: Chris-Johnston

windows-driver-docs-pr/debugger/gflags.md

@@ -39,7 +39,7 @@ GFlags supports the following features:
 
 ### Requirements
 
-To use most GFlags features, you must be a member of the Administrator's group on the computer. For example, to set flags in the registry or in kernel mode, or enable page heap verification.
+To use most GFlags features, you must be a member of the Administrators group on the computer. For example, to set flags in the registry or in kernel mode, or enable page heap verification.
 
 > [!NOTE]
 > Incorrect use of the GFlags tool can degrade system performance or prevent Windows from starting, which might require you to reinstall Windows.
@@ -58,12 +58,9 @@ This section includes:
 
 - [Global Flags dialog](global-flags-dialog-box.md)
 
-- [GFlags examples](gflags-examples.md)
-
-- [Global Flag reference](global-flag-reference.md)
+- [GFlags examples](example-1---displaying-global-flags.md)
 
 ## Related articles
 
-- [GFlags examples](gflags-examples.md)
-- [Global flag reference](global-flag-reference.md)
-- [Tools included in Debugging Tools for Windows](extra-tools.md)
+- [GFlags examples](example-1---displaying-global-flags.md)
+- [Tools included in Debugging Tools for Windows](extra-tools.md)