Update links to SPI, Cellular, Sonar examples

Author: mprse

docs/api/io/SPI.md

@@ -31,4 +31,4 @@ The SPI master generates a clock to synchronously drive a serial bit stream slav
 
 The following example uses the WHOAMI register. The WHOAMI register is an ID register of the slave device. In other words, it's just an example that you can write to a slave's register. In this example, Mbed OS acts as the SPI master, and DigitalOut acts as the slave chip select (cs).
 
-[![View code](https://www.mbed.com/embed/?url=https://os.mbed.com/teams/mbed_example/code/SPI_HelloWorld/)](https://os.mbed.com/teams/mbed_example/code/SPI_HelloWorld/file/3789302f33bc/main.cpp)
+[![View code](https://www.mbed.com/embed/?url=github.com/ARMmbed/mbed-os-examples-docs_only/blob/master/APIs_Drivers/SPI_HelloWorld/)](github.com/ARMmbed/mbed-os-examples-docs_only/blob/master/APIs_Drivers/SPI_HelloWorld/main.cpp)

docs/api/networkinterfaces/CellularInterface.md

@@ -65,7 +65,7 @@ To bring up the network interface:
 
 This example establishes connection with the cellular network using Mbed OS CellularInterface.
 
-[![View code](https://www.mbed.com/embed/?url=https://github.com/ARMmbed/mbed-os-example-cellular)](https://github.com/ARMmbed/mbed-os-example-cellular/blob/mbed-os-5.14/main.cpp)
+[![View code](https://www.mbed.com/embed/?url=github.com/ARMmbed/mbed-os-examples-docs_only/blob/master/APIs_NetworkInterfaces/Cellular/)](github.com/ARMmbed/mbed-os-examples-docs_only/blob/master/APIs_NetworkInterfaces/Cellular/main.cpp)
 
 ## Related content
 

docs/api/platform/Callback.md

@@ -45,4 +45,4 @@ The Callback API provides a convenient way to pass arguments to spawned threads.
 
 Here is an example that uses everything discussed in the [introduction to callbacks](platform.html#callbacks) document in the form of a minimal Sonar class. This example uses a C++ class and method in the Callback.
 
-[![View code](https://www.mbed.com/embed/?url=https://os.mbed.com/teams/mbed_example/code/callback-sonar-example/)](https://os.mbed.com/teams/mbed_example/code/callback-sonar-example/file/1713cdc51510/main.cpp)
+[![View code](https://www.mbed.com/embed/?url=github.com/ARMmbed/mbed-os-examples-docs_only/blob/master/APIs_RTOS/Sonar/)](github.com/ARMmbed/mbed-os-examples-docs_only/blob/master/APIs_RTOS/Sonar/main.cpp)