Standard pin names: few USBTX/USBRX to be replaced

[jeromecoutant]

Docs issue template

USBTX/USBRX still used in:

• docs/api/platform/FileHandle.md
• docs/api/platform/FileHandle.md
• docs/porting/standard_pin_names/pin_names_porting.md

@MarceloSalazar

NB: link https://github.com/ARMmbed/mbed-os-5-docs/edit/development/docs/porting/target/gpio.md#L5 is not correct

Page link

Expected to find...

Found

[ciarmcom]

@jeromecoutant This issue has an incomplete or old issue template.For future reference please use an up to date clone of the repository before raising issues. Many thanks.

[ciarmcom]

Thank you for raising this detailed GitHub issue. I am now notifying our internal issue triagers.
Internal Jira reference: https://jira.arm.com/browse/IOTOSM-4058