Linked USBX readers to published documentation (#279)

* Linked USBX readers to published documentation

The USBX README sent readers to archived Markdown documentation.

I linked the overview to its published HTML guide and the general documentation entry to
the latest release.

Both replacement URLs returned HTTP 200; git diff --check passed.

* Pointed the overview link at the release it ships in

The link introduced here named 6.5.1, so 6.5.2 readers would have been sent to
the previous release's overview from the day it shipped.

It is pinned deliberately rather than floating, so it needs revisiting at each
release, which is the same handling the other version-bearing strings get. The
releases/latest link alongside it is unaffected.

Assisted-by: Claude Code (Opus 5) <noreply@anthropic.com>
Assisted-by: Codex (gpt-6-astra) <noreply@openai.com>

Author: fdesbiens

README.md

@@ -12,7 +12,7 @@ Eclipse ThreadX USBX as part of Eclipse ThreadX has been integrated to the semic
 
 We also provide [samples](https://github.com/azure-rtos/samples) using hero development boards from semiconductors you can build and test with.
 
-See [Overview of Eclipse ThreadX USBX](https://github.com/eclipse-threadx/rtos-docs/blob/main/rtos-docs/usbx/overview-usbx.md) for the high-level overview.
+See [Overview of Eclipse ThreadX USBX](https://threadx.io/releases/6.5.2/usbx/main/overview-usbx.html) for the high-level overview.
 
 ## Repository Structure and Usage
 
@@ -130,7 +130,7 @@ License terms for using Eclipse ThreadX are defined in the LICENSE.txt file of t
 
 The following are references to additional Eclipse ThreadX resources:
 
-- **Product introduction**: https://github.com/eclipse-threadx/rtos-docs
+- **Product introduction**: https://threadx.io/releases/latest
 - **Product issues and bugs, or feature requests**: https://github.com/eclipse-threadx/usbx/issues
 - **TraceX Installer**: https://aka.ms/azrtos-tracex-installer