Copy docs into Zeek repo directly

This is based on commit 2731def9159247e6da8a3191783c89683363689c from the
zeek-docs repo.

doc/scripting/data_struct_table_declaration.zeek

@@ -0,0 +1,19 @@
+event zeek_init()
+    {
+    # Declaration of the table.
+    local ssl_services: table[string] of port;
+
+    # Initialize the table.
+    ssl_services = table(["SSH"] = 22/tcp, ["HTTPS"] = 443/tcp);
+
+    # Insert one key-value pair into the table.
+    ssl_services["IMAPS"] = 993/tcp;
+
+    # Check if the key "SMTPS" is not in the table.
+    if ( "SMTPS" !in ssl_services )
+        ssl_services["SMTPS"] = 587/tcp;
+
+    # Iterate over each key in the table.
+    for ( k in ssl_services )
+        print fmt("Service Name:  %s - Common Port: %s", k, ssl_services[k]);
+    }