Add RST version of ganeti-rapi man page

Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: René Nussbaumer <rn@google.com>

man/ganeti-rapi.rst

+ganeti-rapi(8) Ganeti | Version @GANETI_VERSION@
+================================================
+
+Name
+----
+
+ganeti-rapi - Ganeti remote API daemon
+
+Synopsis
+--------
+
+**ganeti-rapi** [-d] [-f] [--no-ssl] [-K *SSL_KEY_FILE*] [-C
+*SSL_CERT_FILE*]
+
+DESCRIPTION
+-----------
+
+**ganeti-rapi** is the daemon providing a remote API for Ganeti
+clusters.
+
+It is automatically started on the master node, and by default it
+uses SSL encryption. This can be disabled by passing the
+``--no-ssl`` option, or alternatively the certificate used can be
+changed via the ``-C`` option and the key via the ``-K`` option.
+
+The daemon will listen to the "ganeti-rapi" tcp port, as listed in the
+system services database, or if not defined, to port 5080 by default.
+
+See the *Ganeti remote API* documentation for further information.
+
+Requests are logged to ``@LOCALSTATEDIR@/log/ganeti/rapi-daemon.log``,
+in the same format as for the node and master daemon.
+
+ACCESS CONTROLS
+---------------
+
+All query operations are allowed without authentication. Only the
+modification operations require authentication, in the form of basic
+authentication.
+
+The users and their rights are defined in a file named rapi_users,
+located in the ``@LOCALSTATEDIR@/lib/ganeti`` directory. The users
+should be listed one per line, in the following format::
+
+    username password options
+
+Currently the *options* field should equal the string ``write`` in
+order to actually give write permission for the given users. Example::
+
+    rclient   secret    write
+    guest     testpw
+
+The first user (*rclient*) has read-write rights, whereas the second
+user (*guest*) only has read (query) rights, and as such is no
+different than not using authentication at all.
+
+More details (including on how to use hashed passwords) can be found
+in the Ganeti documentation.