ad6676evb: Update project doc

Signed-off-by: sarpadi <sergiu.arpadi@analog.com>

Author: sarpadi

docs/projects/ad6676evb/index.rst

@@ -41,12 +41,18 @@ Supported carriers
      - Carrier
      - FMC slot
    * - :adi:`EVAL-AD6676`
-     - :xilinx:`VC707`
+     - :xilinx:`VC707` *
      - FMC1 HPC
    * -
      - :xilinx:`ZC706`
      - FMC HPC
 
+.. admonition:: Legend
+   :class: note
+
+   - ``*`` removed; last release that supports this project on this carrier is
+      :git-hdl:`hdl_2023_r2 <hdl_2023_r2:projects/ad6676_evb/vc707>`
+
 Block design
 -------------------------------------------------------------------------------