L2SS-434: Added a hierachy to faq

docs/source/faq.rst

 FAQ
 ===================================
 
-*Q: My device is unreachable, but the device logs say it's running fine.*
+Connecting to devices
+--------------------------------------------------------------------------------------------------------------
+
+My device is unreachable, but the device logs say it's running fine?
+``````````````````````````````````````````````````````````````````````````````````````````````````````````````
 
 The ``$HOSTNAME`` may have been incorrectly guessed by ``docker-compose/Makefile``, or you accidently set it to an incorrect value. See :ref:`corba`.
 
-*Q: I get "API_CorbaException: TRANSIENT CORBA system exception: TRANSIENT_NoUsableProfile" when trying to connect to a device.*
+I get "API_CorbaException: TRANSIENT CORBA system exception: TRANSIENT_NoUsableProfile" when trying to connect to a device?
+````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````
 
 The ``$HOSTNAME`` may have been incorrectly guessed by ``docker-compose/Makefile``, or you accidently set it to an incorrect value. See :ref:`corba`.
 
-*Q: The elk container won't start, saying "max virtual memory areas vm.max_map_count [65530] is too low"?*
-
-The ELK stack needs the ``vm.max_map_count`` sysctl kernel parameter to be at least 262144 to run. See :ref:`elk-kernel-settings`.
+Docker
+--------------------------------------------------------------------------------------------------------------
 
-*Q: How do I prevent my containers from starting when I boot my computer?*
+How do I prevent my containers from starting when I boot my computer?
+````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````
 
 You have to explicitly stop a container to prevent it from restarting. Use::
 
@@ -22,7 +27,11 @@ You have to explicitly stop a container to prevent it from restarting. Use::
 
 or plain ``make stop`` to stop all of them.
 
-*Q: Some SSTs/XSTs packets do arrive, but not all, and/or the matrices remain zero?*
+SSTs/XSTs
+--------------------------------------------------------------------------------------------------------------
+
+Some SSTs/XSTs packets do arrive, but not all, and/or the matrices remain zero?
+``````````````````````````````````````````````````````````````````````````````````````````````````````````````
 
 So ``sst.nof_packets_received`` / ``xst.nof_packets_received`` is increasing, telling you packets are arriving. But they're apparently dropped or contain zeroes. First, check the following settings:
 
@@ -36,7 +45,8 @@ Furthermore, the ``sst`` and ``xst`` devices expose several packet counters to i
 - ``nof_packets_dropped_R`` increases if packets could not be processed because the processing queue is full, so the CPU cannot keep up with the flow,
 - ``nof_payload_errors_R`` increases if the packet was marked by the FPGA to have an invalid payload, which causes the device to discard the packet,
 
-*Q: I am not receiving any XSTs and/or SSTs packets from SDP!*
+I am not receiving any XSTs and/or SSTs packets from SDP!
+``````````````````````````````````````````````````````````````````````````````````````````````````````````````
 
 Are you sure? If ``sst.nof_packets_received`` / ``xst.nof_packets_received`` is actually increasing, the packets are arriving, but are not parsable by the SST/XST device. If so, see the previous question.
 
@@ -60,7 +70,8 @@ Many settings need to be correct for the statistics emitted by the SDP FPGAs to
 
 If this fails, see the next question.
 
-*Q: I am still not receiving XSTs and/or SSTs, even though the settings appear correct!*
+I am still not receiving XSTs and/or SSTs, even though the settings appear correct!
+``````````````````````````````````````````````````````````````````````````````````````````````````````````````
 
 Let's see where the packets get stuck. Let us assume your MTU=9000 network interface is called ``em2`` (see ``ip addr`` to check):
 
@@ -97,3 +108,11 @@ Let's see where the packets get stuck. Let us assume your MTU=9000 network inter
   - If not, Linux is not routing the packets to the docker container correctly.
 
 - If still on error was found, you've likely hit a bug in our software.
+
+Other containers
+--------------------------------------------------------------------------------------------------------------
+
+The ELK container won't start, saying "max virtual memory areas vm.max_map_count [65530] is too low"?
+``````````````````````````````````````````````````````````````````````````````````````````````````````````````
+
+The ELK stack needs the ``vm.max_map_count`` sysctl kernel parameter to be at least 262144 to run. See :ref:`elk-kernel-settings`.