doc: update markdown file names and locations

Moved files to appropriate location and updated naming style for some of them. Fixes: #31741
nodejs · DavenportEmma · Feb 14, 2020 · Feb 14, 2020 · Feb 14, 2020 · Feb 14, 2020
commit 5105790568e909f378dfb229099c1bc26a54932f
diff --git a/doc/guides/updating-root-certs.md → doc/guides/maintaining-root-certs.md b/doc/guides/updating-root-certs.md → doc/guides/maintaining-root-certs.md
@@ -1,4 +1,4 @@
-# Updating the Root Certificates
+# Maintaining the Root Certificates
 
 Node.js contains a compiled-in set of root certificates used as trust anchors
 for TLS certificate validation.

diff --git a/doc/offboarding.md → doc/guides/offboarding.md b/doc/offboarding.md → doc/guides/offboarding.md
diff --git a/doc/onboarding-extras.md → doc/guides/onboarding-extras.md b/doc/onboarding-extras.md → doc/guides/onboarding-extras.md
diff --git a/doc/onboarding.md → doc/guides/onboarding.md b/doc/onboarding.md → doc/guides/onboarding.md
diff --git a/doc/releases.md → doc/guides/releases.md b/doc/releases.md → doc/guides/releases.md
diff --git a/doc/guides/security_release_process.md → doc/guides/security-release-process.md b/doc/guides/security_release_process.md → doc/guides/security-release-process.md