Update README.rst

To reflect additional Runtime Configuration Options and
supported Linux distributions

README.rst

@@ -2,23 +2,32 @@ RIPE Atlas Software Probe
 =========================
 
 This is the source code for RIPE Atlas software probes. Currently this
-source code supports building a RPM package for CentOS 7. See
+source code supports building an RPM package for CentOS 7 and CentOS 8,
+as well as various Debian versions and Debian-based distributions. See
 INSTALL.rst for installation instructions.
 
-Unless specified otherwise, this code is licensed under the GPLv3. A copy
-of the license can be found in LICENSE.
+Unless specified otherwise, this code is licensed under the GPLv3. A
+copy of the license can be found in LICENSE.
 
 Note
 ----
 
 The software probe uses TCP ports 2023 and 8080 internally. If another
-service is using these ports then the probe will not function correctly.
+service is using these ports, then the probe will not function
+correctly. To avoid conflicts, the runtime configuration options
+described below are available to make the probe use different port
+numbers.
 
 Runtime Configuration Options
 -----------------------------
 
-Currently there is one runtime configuration option that enables sending
-interface traffic statistics as Atlas measurement results. 
-This option can be enabled by creating the file
-/var/atlas-probe/state/config.txt and adding the line 'RXTXRPT=yes'.
+Currently there are three runtime configuration options available. To
+use them, create the file /var/atlas-probe/state/config.txt and add a
+line per desired configuration setting as per the following:
 
+- Set 'RXTXRPT=yes' to enable sending of interface traffic statistics as
+  Atlas measurement results.
+- Set TELNETD_PORT to an integer value to make the probe use that TCP
+  port number instead of 2023, e.g., 'TELNETD_PORT=52023'.
+- Set HTTP_POST_PORT to an integer value to make the probe use that TCP
+  port number instead of 8080, e.g., 'HTTP_POST_PORT=58080'.