docs(common): improving documentation

- update esp_modem to use esp_docs
- migrated docs from github pages to docs.espressif.com

docs/utils.sh

@@ -0,0 +1,18 @@
+# Bash helper functions for adding SSH keys
+
+function add_ssh_keys() {
+  local key_string="${1}"
+  mkdir -p ~/.ssh
+  chmod 700 ~/.ssh
+  echo -n "${key_string}" >~/.ssh/id_rsa_base64
+  base64 --decode --ignore-garbage ~/.ssh/id_rsa_base64 >~/.ssh/id_rsa
+  chmod 600 ~/.ssh/id_rsa
+}
+
+function add_doc_server_ssh_keys() {
+  local key_string="${1}"
+  local server_url="${2}"
+  local server_user="${3}"
+  add_ssh_keys "${key_string}"
+  echo -e "Host ${server_url}\n\tStrictHostKeyChecking no\n\tUser ${server_user}\n" >>~/.ssh/config
+}