Update links to examples

[mprse]

Update links to the following examples:

• Platform,
• IO,
• RTOS,
• NFC,
• Network,
• Storage.

Related PR that brings example to https://github.com/ARMmbed/mbed-os-examples-docs_only:

• Bring platform layer examples mbed-os-examples-docs_only#70
• Add RTOS examples mbed-os-examples-docs_only#71
• Add IO examples: SPIMaster and I2CSlave mbed-os-examples-docs_only#75
• Add Network related examples mbed-os-examples-docs_only#80

@AnotherButler Please review. Not sure if this is done in the correct way. I think we should wait with this one until the above list is merged.

[jamesbeyond]

I believe all the code dependency been merged. could you review this PR @AnotherButler

[AnotherButler]

For cellular, do we use the one in this PR or the official example, which should be kept up to date: https://github.com/ARMmbed/mbed-os-example-cellular/blob/mbed-os-5.15/main.cpp? @adbridge @jamesbeyond

[adbridge]

@AnotherButler I think this is a question for @AnttiKauppila ?

[jamesbeyond]

For cellular, do we use the one in this PR or the official example, which should be kept up to date: https://github.com/ARMmbed/mbed-os-example-cellular/blob/mbed-os-5.15/main.cpp? @adbridge @jamesbeyond

the content of
https://github.com/ARMmbed/mbed-os-examples-docs_only/blob/master/APIs_NetworkInterfaces/Cellular/main.cpp
and
https://github.com/ARMmbed/mbed-os-example-cellular/blob/mbed-os-5.15/main.cpp
are identical.

I agree to keep one, maybe https://github.com/ARMmbed/mbed-os-example-cellular/blob/mbed-os-5.15/main.cpp would be better

[jamesbeyond]

@mprse could you change the link pointing to https://github.com/ARMmbed/mbed-os-example-cellular/blob/master/main.cpp

Don't worries about https://github.com/ARMmbed/mbed-os-examples-docs_only/tree/master/APIs_NetworkInterfaces/Cellular, I'll create a PR to remove that

[jamesbeyond]

Hi @AnotherButler, I updated this link, this PR is good to go

[AnotherButler]

Thanks for the PR 👍