Update documentation to create an empty wal file

Author: Ed Coleman

_docs-2/troubleshooting/advanced.md

@@ -249,21 +249,29 @@ metadata table!), the following process can be followed to create a valid, empty
 WAL file. Run the following commands as the Accumulo unix user (to ensure that
 the proper file permissions in HDFS)
 
-    $ echo -n -e '--- Log File Header (v2) ---\x00\x00\x00\x00' > empty.wal
+```
+$ UUID=$(uuidgen); \
+echo -n -e '--- Log File Header (v4) ---U+1F47B$'"${UUID}"'\x00\x00\x00\x00' > "${UUID}".wal; \
+echo 'created: '"${UUID}"'.wal'
+```
 
-The above creates a file with the text "--- Log File Header (v2) ---" and then
-four bytes. You should verify the contents of the file with a hexdump tool.
+The above creates a file with the text "--- Log File Header (v4) ---" a unicode character to flag no decryption 
+parameters, a UUID and then four bytes. The file created will be `[uuid]`.wal and the name is echoed to the command
+line. You should verify the contents of the file with a hexdump tool.
 
-Then, place this empty WAL in HDFS and then replace the corrupt WAL file in HDFS
-with the empty WAL.
+Then, place this empty WAL in HDFS and then replace the corrupt WAL file in HDFS with the empty WAL for the 
+tserver / host pair with the following hdfs commands:
 
-    $ hdfs dfs -moveFromLocal empty.wal /user/accumulo/empty.wal
-    $ hdfs dfs -mv /user/accumulo/empty.wal /accumulo/wal/tserver-4.example.com+10011/26abec5b-63e7-40dd-9fa1-b8ad2436606e
+    $ hdfs dfs -moveFromLocal [uuid].wal /user/accumulo/[uuid].wal
+    $ hdfs dfs -mv /user/accumulo/[uuid].wal /accumulo/wal/[tserver+port]/[uuid]
 
-After the corrupt WAL file has been replaced, the system should automatically recover.
-It may be necessary to restart the Accumulo Manager process as an exponential
-backup policy is used which could lead to a long wait before Accumulo will
-try to re-load the WAL file.
+Note:
+- the `+` separator for port.
+- the wal file is the uuid, without an extension
+
+After the corrupt WAL file has been replaced, the system should automatically recover. It may be necessary to restart 
+the Accumulo Manager process as an exponential backup policy is used which could lead to a long wait before Accumulo 
+will try to re-load the WAL file.
 
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