docs: restore lost auth proxy logs

These came from f2a789ea98 which unfortunately added the docs to
the auto generated files.

cmd/serve/proxy/proxy.go

@@ -29,6 +29,10 @@ rclone will use that program to generate backends on the fly which
 then are used to authenticate incoming requests.  This uses a simple
 JSON based protocl with input on STDIN and output on STDOUT.
 
+**PLEASE NOTE:** |--auth-proxy| and |--authorized-keys| cannot be used
+together, if |--auth-proxy| is set the authorized keys option will be
+ignored.
+
 There is an example program
 [bin/test_proxy.py](https://github.com/rclone/rclone/blob/master/test_proxy.py)
 in the rclone source code.
@@ -46,7 +50,8 @@ This config generated must have this extra parameter
 And it may have this parameter
 - |_obscure| - comma separated strings for parameters to obscure
 
-For example the program might take this on STDIN
+If password authentication was used by the client, input to the proxy
+process (on STDIN) would look similar to this:
 
 |||
 {
@@ -55,7 +60,17 @@ For example the program might take this on STDIN
 }
 |||
 
-And return this on STDOUT
+If public-key authentication was used by the client, input to the
+proxy process (on STDIN) would look similar to this:
+
+|||
+{
+	"user": "me",
+	"public_key": "AAAAB3NzaC1yc2EAAAADAQABAAABAQDuwESFdAe14hVS6omeyX7edc...JQdf"
+}
+|||
+
+And as an example return this on STDOUT
 
 |||
 {
@@ -69,7 +84,7 @@ And return this on STDOUT
 |||
 
 This would mean that an SFTP backend would be created on the fly for
-the |user| and |pass| returned in the output to the host given.  Note
+the |user| and |pass|/|public_key| returned in the output to the host given.  Note
 that since |_obscure| is set to |pass|, rclone will obscure the |pass|
 parameter before creating the backend (which is required for sftp
 backends).
@@ -81,8 +96,8 @@ in the output and the user to |user|. For security you'd probably want
 to restrict the |host| to a limited list.
 
 Note that an internal cache is keyed on |user| so only use that for
-configuration, don't use |pass|.  This also means that if a user's
-password is changed the cache will need to expire (which takes 5 mins)
+configuration, don't use |pass| or |public_key|.  This also means that if a user's
+password or public-key is changed the cache will need to expire (which takes 5 mins)
 before it takes effect.
 
 This can be used to build general purpose proxies to any kind of