chore: remove invalid trailing comma from the documentation

Remove invalid trailing comma from a json body of a request in the
documentation.

Co-Authored-By: Steven Wirges <[email protected]>
Signed-off-by: Egor Lazarchuk <[email protected]>

Author: stvnwrgs

docs/snapshotting/snapshot-support.md

@@ -266,7 +266,7 @@ curl --unix-socket /tmp/firecracker.socket -i \
     -d '{
             "snapshot_type": "Full",
             "snapshot_path": "./snapshot_file",
-            "mem_file_path": "./mem_file",
+            "mem_file_path": "./mem_file"
     }'
 ```