docs: Update outdated link target URLs (#2721)

Author: sarina

credentials/apps/edx_credentials_extensions/migrations/0001_initial.py

@@ -12,7 +12,7 @@ def add_siteconfiguration_data(apps, schema_editor):
         "privacy_policy_url": "https://www.edx.org/edx-privacy-policy",
         "homepage_url": "https://www.edx.org",
         "company_name": "edX Inc.",
-        "certificate_help_url": "https://edx.readthedocs.org/projects/edx-guide-for-students/en/latest/SFD_certificates.html#web-certificates",
+        "certificate_help_url": "https://docs.openedx.org/en/latest/educators/concepts/open_edx_platform/about_certificates.html",
         "theme_name": "edx.org",
     }
     SiteConfiguration.objects.update_or_create(site=site, defaults=defaults)

docs/internationalization.rst

@@ -95,7 +95,7 @@ translations using the following steps and commands that are provided in the cre
 
 #. Finally, stage your updated translation files to be committed with the rest of your work.
 
-.. _internationalization coding guidelines: http://edx.readthedocs.io/projects/edx-developer-guide/en/latest/internationalization/i18n.html#internationalization-coding-guidelines
+.. _internationalization coding guidelines: https://docs.openedx.org/en/latest/developers/references/developer_guide/internationalization/i18n.html
 .. _Django internationalization documentation: https://docs.djangoproject.com/en/1.11/topics/i18n
 .. _LANGUAGE_CODE setting: https://docs.djangoproject.com/en/1.11/ref/settings/#language-code
 .. _Django docs for language_code: https://docs.djangoproject.com/en/1.11/topics/i18n/#term-language-code