docs: Update README docs links (#946)

Update README docs links to point at release branch. The goal of this
change is to avoid confusing users when we merge major changes (e.g. the
executable rename, the dotnet tool install option, etc.) to main but
have not yet released them. With this update, the documentation should
align with the latest release.

Author: ldennington

README.md

@@ -22,7 +22,8 @@ GCM replaces both the .NET Framework-based
 
 ## Install
 
-See [installation instructions][install] for your operating system.
+See the [installation instructions][install] for the current version of GCM for
+install options for your operating system.
 
 ## Current status
 
@@ -119,24 +120,24 @@ When using GitHub logos, please be sure to follow the
 [bitbucket]: https://bitbucket.org
 [bitbucket-ssh]: https://confluence.atlassian.com/bitbucket/ssh-keys-935365775.html
 [build-status-badge]: https://github.com/GitCredentialManager/git-credential-manager/actions/workflows/continuous-integration.yml/badge.svg
-[docs-index]: docs/README.md
+[docs-index]: https://github.com/GitCredentialManager/git-credential-manager/blob/release/docs/README.md
 [dotnet]: https://dotnet.microsoft.com
 [git-credential-helper]: https://git-scm.com/docs/gitcredentials
 [gcm]: https://github.com/GitCredentialManager/git-credential-manager
 [gcm-coc]: CODE_OF_CONDUCT.md
 [gcm-commit-12294990]: https://github.com/git/git/commit/12294990c90e043862be9eb7eb22c3784b526340
 [gcm-contributing]: CONTRIBUTING.md
-[gcm-credstores]: docs/credstores.md
+[gcm-credstores]: https://github.com/GitCredentialManager/git-credential-manager/blob/release/docs/credstores.md
 [gcm-for-mac-and-linux]: https://github.com/microsoft/Git-Credential-Manager-for-Mac-and-Linux
 [gcm-for-windows]: https://github.com/microsoft/Git-Credential-Manager-for-Windows
-[gcm-http-proxy]: docs/netconfig.md#http-proxy
+[gcm-http-proxy]: https://github.com/GitCredentialManager/git-credential-manager/blob/release/docs/netconfig.md#http-proxy
 [gcm-license]: LICENSE
-[gcm-usage]: docs/usage.md
-[gcm-windows-broker]: docs/windows-broker.md
+[gcm-usage]: https://github.com/GitCredentialManager/git-credential-manager/blob/release/docs/usage.md
+[gcm-windows-broker]: https://github.com/GitCredentialManager/git-credential-manager/blob/release/docs/windows-broker.md
 [git-tools-credential-storage]: https://git-scm.com/book/en/v2/Git-Tools-Credential-Storage
 [github]: https://github.com
 [github-ssh]: https://help.github.com/en/articles/connecting-to-github-with-ssh
 [github-logos]: https://github.com/logos
-[install]: docs/install.md
+[install]: https://github.com/GitCredentialManager/git-credential-manager/blob/release/docs/install.md
 [ms-package-repos]: https://packages.microsoft.com/repos/
 [workflow-status]: https://github.com/GitCredentialManager/git-credential-manager/actions/workflows/continuous-integration.yml