Fix links in chapter 16

Author: namcios

16_1_Accessing_Bitcoind_with_C.md

@@ -147,7 +147,7 @@ bitcoinrpc_global_cleanup();
 
 ### Test the Test Code
 
-Test code can be found at [15_1_testbitcoin.c in the src directory](src/15_1_testbitcoin.c). Download it to your testnet machine, then insert the correct RPC password (and change the RPC user if you didn't create your server with StandUp).
+Test code can be found at [16_1_testbitcoin.c in the src directory](src/16_1_testbitcoin.c). Download it to your testnet machine, then insert the correct RPC password (and change the RPC user if you didn't create your server with StandUp).
 
 You can compile and run this as follows:
 ```
@@ -213,7 +213,7 @@ printf("Block Count: %d\n",blocks);
 
 ### Test the Info Code
 
-Retrieve the test code from [the src directory](src/15_1_getmininginfo.c).
+Retrieve the test code from [the src directory](src/16_1_getmininginfo.c).
 ```
 $ cc getmininginfo.c -lbitcoinrpc -ljansson -o getmininginfo
 $ ./getmininginfo 

16_2_Programming_Bitcoind_with_C.md

@@ -2,7 +2,7 @@
 
 > :information_source: **NOTE:** This section has been recently added to the course and is an early draft that may still be awaiting review. Caveat reader.
 
-[§15.1](15_1_Accessing_Bitcoind_with_C.md) laid out the methodology for creating C programs using RPC and JSON libraries. We're now going to show the potential of those C libraries by laying out a simplistic, first cut of an actual Bitcoin program.
+[§16.1](16_1_Accessing_Bitcoind_with_C.md) laid out the methodology for creating C programs using RPC and JSON libraries. We're now going to show the potential of those C libraries by laying out a simplistic, first cut of an actual Bitcoin program.
 
 ## Plan for Your Code
 
@@ -324,7 +324,7 @@ The entire code, with a _little_ more error-checking appears in the Appendix.
 
 ## Test Your Code
 
-The complete code can be found in the [src directory](src/15_2_sendtoaddress.c).
+The complete code can be found in the [src directory](src/16_2_sendtoaddress.c).
 
 Compile this as usual:
 ```

16_3_Receiving_Bitcoind_Notifications_with_C.md

@@ -121,7 +121,7 @@ Of course when you're done, you should clean up:
 
 ### Test the Notification Code
 
-The source code is in the [src directory](src/15_3_chainlistener.c) as usual. You should compile it:
+The source code is in the [src directory](src/16_3_chainlistener.c) as usual. You should compile it:
 ```
 $ cc -o chainlistener chainlistener.c -I/usr/local/include -L/usr/local/lib -lzmq -lczmq
 ```