Documentation: trace: Refactor toctree

Refactor table of contents of kernel tracing subsystem docs to improve
clarity, structure, and organization:

- Reformat sections and add appropriate headings
- Improve section grouping and refine descriptions for each group
- Add docs intro paragraph

Signed-off-by: Purva Yeshi <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
[Bagas: massage commit message and address reviews]
Co-developed-by: Bagas Sanjaya <[e-mail]>
Signed-off-by: Bagas Sanjaya <[e-mail]>
Acked-by: Steven Rostedt (Google) <[e-mail]>
Signed-off-by: Jonathan Corbet <[e-mail]>

Documentation/trace/index.rst

···
-==========================
-Linux Tracing Technologies
-==========================
+================================
+Linux Tracing Technologies Guide
+================================
+
+Tracing in the Linux kernel is a powerful mechanism that allows
+developers and system administrators to analyze and debug system
+behavior. This guide provides documentation on various tracing
+frameworks and tools available in the Linux kernel.
+
+Introduction to Tracing
+-----------------------
+
+This section provides an overview of Linux tracing mechanisms
+and debugging approaches.
 
 .. toctree::
    :maxdepth: 1
 
-   ftrace-design
+   debugging
+   tracepoints
    tracepoint-analysis
+   ring-buffer-map
+
+Core Tracing Frameworks
+-----------------------
+
+The following are the primary tracing frameworks integrated into
+the Linux kernel.
+
+.. toctree::
+   :maxdepth: 1
+
    ftrace
+   ftrace-design
    ftrace-uses
-   fprobe
    kprobes
    kprobetrace
-   uprobetracer
    fprobetrace
-   tracepoints
+   fprobe
+   ring-buffer-design
+
+Event Tracing and Analysis
+--------------------------
+
+A detailed explanation of event tracing mechanisms and their
+applications.
+
+.. toctree::
+   :maxdepth: 1
+
    events
    events-kmem
    events-power
    events-nmi
    events-msr
-   mmiotrace
+   boottime-trace
    histogram
    histogram-design
-   boottime-trace
-   debugging
-   hwlat_detector
-   osnoise-tracer
-   timerlat-tracer
+
+Hardware and Performance Tracing
+--------------------------------
+
+This section covers tracing features that monitor hardware
+interactions and system performance.
+
+.. toctree::
+   :maxdepth: 1
+
    intel_th
-   ring-buffer-design
-   ring-buffer-map
    stm
    sys-t
    coresight/index
-   user_events
    rv/index
    hisi-ptt
+   mmiotrace
+   hwlat_detector
+   osnoise-tracer
+   timerlat-tracer
+
+User-Space Tracing
+------------------
+
+These tools allow tracing user-space applications and
+interactions.
+
+.. toctree::
+   :maxdepth: 1
+
+   user_events
+   uprobetracer
+
+Additional Resources
+--------------------
+
+For more details, refer to the respective documentation of each
+tracing tool and framework.
+
+.. only:: subproject and html
+
+   Indices
+   =======
+
+   * :ref:`genindex`