Add support for Bootloader Ping

[mablem8]

• Add a description of Bootloader Ping to DOCUMENTATION.md
• Add an implementation of Bootloader Ping to c-implementation/tab.c
• Add an implementation of Bootloader Ping to python-implementation/tab.py
• Add testing of Bootloader Ping in python-examples/tx/tx_example.py
• Test support for Bootloader Ping with c-examples/cdh-monolithic and python-examples/tx

[ChadTaylor17]

Commit: b2eeab1b9c816191400148c873a492c78d4d1663

Tested successfully: Bootloader mode: txcmd: bootloader_ping hw_id:0x1234 msg_id:0x0007 src:gnd dst:cdh reply: bootloader_ack hw_id:0x1234 msg_id:0x0007 src:cdh dst:gnd reason:0x00(pong)

App mode: txcmd: bootloader_ping hw_id:0x1234 msg_id:0x0007 src:gnd dst:cdh reply: common_nack hw_id:0x1234 msg_id:0x0007 src:cdh dst:gnd

[mablem8]

For future posts, link to the changes that address each issue bullet:

• ✅ A description of Bootloader Ping has been added here
  • ❌ The description has not been linked in the Overview
  • The bootloader ping command checks whether the bootloader is active.
• ✅ An implementation of Bootloader Ping has been added to tab.c
• ✅ An implementation of Bootloader Ping has been added to tab.py
• ✅ Adds testing of Bootloader Ping in tx_example.py
• I will replicate the test after the above updates have been made

[ChadTaylor17]

Commit: 51ec4fbfae109575a13017a01068f05b4245f500

[mablem8]

This commit looks good!

When submitting an Issue fix, use the following format:

• A description of Bootloader Ping has been added here
• An implementation of Bootloader Ping has been added to tab.c
• An implementation of Bootloader Ping has been added to tab.py
• Testing of Bootloader Ping has been added to tx_example.py
• Test output for Bootloader Ping:

txcmd: bootloader_ping hw_id:0x1234 msg_id:0x0007 src:gnd dst:cdh
reply: bootloader_ack hw_id:0x1234 msg_id:0x0007 src:cdh dst:gnd reason:0x00(pong)