Add ability to specify custom names in the OAuth login buttons (#214)

docs/configuration/cheat-sheet.md

@@ -24,9 +24,11 @@
 | gitlab.client-key     | OG_GITLAB_CLIENT_KEY     | none                  | The client key for the GitLab OAuth application.                                                                                                                                                                                 |
 | gitlab.secret         | OG_GITLAB_SECRET         | none                  | The secret for the GitLab OAuth application.                                                                                                                                                                                     |
 | gitlab.url            | OG_GITLAB_URL            | `https://gitlab.com/` | The URL of the GitLab instance.                                                                                                                                                                                                  |
+| gitlab.name           | OG_GITLAB_NAME           | `GitLab`              | The name of the GitLab instance. It is displayed in the OAuth login button.                                                                                                                                                                                                  |
 | gitea.client-key      | OG_GITEA_CLIENT_KEY      | none                  | The client key for the Gitea OAuth application.                                                                                                                                                                                  |
 | gitea.secret          | OG_GITEA_SECRET          | none                  | The secret for the Gitea OAuth application.                                                                                                                                                                                      |
 | gitea.url             | OG_GITEA_URL             | `https://gitea.com/`  | The URL of the Gitea instance.                                                                                                                                                                                                   |
+| gitea.name            | OG_GITEA_NAME            | `Gitea`               | The name of the Gitea instance. It is displayed in the OAuth login button.                                                                                                                                                                                                  |
 | oidc.client-key       | OG_OIDC_CLIENT_KEY       | none                  | The client key for the OpenID application.                                                                                                                                                                                       |
 | oidc.secret           | OG_OIDC_SECRET           | none                  | The secret for the OpenID application.                                                                                                                                                                                           |
 | oidc.discovery-url    | OG_OIDC_DISCOVERY_URL    | none                  | Discovery endpoint of the OpenID provider.                                                                                                                                                                                       |