document how remote exec/copy is used

Signed-off-by: Steven Armstrong <steven@icarus.ethz.ch>

doc/man/man7/cdist-remote-exec-copy.text

@@ -1,29 +1,40 @@
 cdist-remote-exec-copy(7)
 =========================
 Nico Schottelius <nico-cdist--@--schottelius.org>
-STEVEN HERE
 
 
 NAME
 ----
-cdist-remote-exec-copy - How to get use remote exec and copy
+cdist-remote-exec-copy - How to use remote exec and copy
 
 
 INTRO
--------
+-----
-What it is, how it works
+Cdist interacts with the target host in two ways:
+- it executes code (__remote_exec)
+- and it copies files (__remote_copy)
+
+By default this is accomplished with ssh and scp respectively.
+The default implementations used by cdist are:
+__remote_exec: ssh -o User=root -q
+__remote_copy: scp -o User=root -q
+
+The user can override these defaults by providing custom implementations and
+passing them to cdist with the --remote-exec and/or --remote-copy arguments.
+
+For __remote_exec, the custom implementation must behave as if it where ssh.
+For __remote_copy, it must behave like scp.
+
+With this simple interface the user can take total control of how cdist
+interacts with the target when required, while the default implementation 
+remains as simple as possible.
 
 
 EXAMPLES
 --------------
-nfsroot, sudo (?), what exists
+See cdist/other/examples/remote/ for some example implementations.
 
 
-HACKER INFORMATION
-------------------
-Not sure if needed, but may be helpful to explain how it
-works internally
-
 SEE ALSO
 --------
 - cdist(7)