net: ena: Fix rst format issues in readme

This patch fixes a warning in the ena documentation
file identified by the kernel automatic tools.
The patch also adds a missing newline between
sections.
Signed-off-by: David Arinzon <darinzon@amazon.com>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202306171804.U7E92zoE-lkp@intel.com/Reviewed-by: Simon Horman <simon.horman@corigine.com>
Link: https://lore.kernel.org/r/20230620133544.32584-1-darinzon@amazon.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Documentation/networking/device_drivers/ethernet/amazon/ena.rst

@@ -38,6 +38,7 @@ debug logs.
 
 Some of the ENA devices support a working mode called Low-latency
 Queue (LLQ), which saves several more microseconds.
+
 ENA Source Code Directory Structure
 ===================================
 
@@ -206,6 +207,7 @@ More information about Adaptive Interrupt Moderation (DIM) can be found in
 Documentation/networking/net_dim.rst
 
 .. _`RX copybreak`:
+
 RX copybreak
 ============
 The rx_copybreak is initialized by default to ENA_DEFAULT_RX_COPYBREAK