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 <[e-mail]>
Reported-by: kernel test robot <[e-mail]>
Closes: https://lore.kernel.org/oe-kbuild-all/[e-mail]/
Reviewed-by: Simon Horman <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

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

···
 
 Some of the ENA devices support a working mode called Low-latency
 Queue (LLQ), which saves several more microseconds.
+
 ENA Source Code Directory Structure
 ===================================
 
···
 Documentation/networking/net_dim.rst
 
 .. _`RX copybreak`:
+
 RX copybreak
 ============
 The rx_copybreak is initialized by default to ENA_DEFAULT_RX_COPYBREAK