Update links in about_Environment_Variables.md

about_*.md links are case-sensitive on sane platforms

Author: derekm

reference/5.1/Microsoft.PowerShell.Core/About/about_Environment_Variables.md

@@ -452,8 +452,8 @@ The environment variables that store preferences include:
 [03]: #powershell-environment-variables
 [04]: about_Environment_Provider.md
 [05]: about_Execution_Policies.md
-[06]: about_preference_variables.md
-[07]: about_profiles.md
+[06]: about_Preference_Variables.md
+[07]: about_Profiles.md
 [08]: about_PSModulePath.md
-[11]: about_variables.md
+[11]: about_Variables.md
 [14]: xref:PowerShellGet.Install-Module

reference/7.4/Microsoft.PowerShell.Core/About/about_Environment_Variables.md

@@ -562,12 +562,12 @@ or `NO_COLOR` environment variables.
 [03]: #powershell-environment-variables
 [04]: about_Environment_Provider.md
 [05]: about_Execution_Policies.md
-[06]: about_preference_variables.md
-[07]: about_profiles.md
+[06]: about_Preference_Variables.md
+[07]: about_Profiles.md
 [08]: about_PSModulePath.md
 [09]: about_Telemetry.md
 [10]: about_Update_Notifications.md
-[11]: about_variables.md
+[11]: about_Variables.md
 [12]: https://no-color.org/
 [13]: https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html
 [14]: xref:PowerShellGet.Install-Module

reference/7.6/Microsoft.PowerShell.Core/About/about_Environment_Variables.md

@@ -563,12 +563,12 @@ or `NO_COLOR` environment variables.
 [03]: #powershell-environment-variables
 [04]: about_Environment_Provider.md
 [05]: about_Execution_Policies.md
-[06]: about_preference_variables.md
-[07]: about_profiles.md
+[06]: about_Preference_Variables.md
+[07]: about_Profiles.md
 [08]: about_PSModulePath.md
 [09]: about_Telemetry.md
 [10]: about_Update_Notifications.md
-[11]: about_variables.md
+[11]: about_Variables.md
 [12]: https://no-color.org/
 [13]: https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html
 [14]: xref:PowerShellGet.Install-Module