update docs of age about ssh support

Signed-off-by: haoqixu <[email protected]>

content/en/docs/_index.md

@@ -232,7 +232,13 @@ one per line. Lines beginning with `#` are considered comments and
 ignored. Each identity will be tried in sequence until one is able to
 decrypt the data.
 
-Encrypting with SSH keys via age is not yet supported by SOPS.
+Encrypting with SSH keys via age is also supported by SOPS. You can use SSH public keys
+("ssh-ed25519 AAAA...", "ssh-rsa AAAA...") as age recipients when encrypting a file.
+When decrypting a file, SOPS will look for `~/.ssh/id_ed25519` and fallbacks to
+`~/.ssh/id_rsa`. You can specify the location of the private key manually by setting
+the environment variableuse **SOPS_AGE_SSH_PRIVATE_KEY_FILE**.
+
+Note that only `ssh-rsa` and `ssh-ed25519` are supported.
 
 ## Encrypting using GCP KMS