docs: rust: arch-support: use simple table

reST's list tables are quite hard to read when inspecting
the source of the documents.

There are other 3 ways to create tables in reST: grids tables,
CSV tables and simple tables. Plus, of course, the "manual"
way of using a code block with custom formatting.

Use simple tables since they are lightweight and we do not need
the features of the more complex tables.

Suggested-by: Akira Yokosawa <[email protected]>
Suggested-by: Jonathan Corbet <[email protected]>
Signed-off-by: Miguel Ojeda <[email protected]>

Author: ojeda

Documentation/rust/arch-support.rst

@@ -12,25 +12,14 @@ which uses ``libclang``.
 Below is a general summary of architectures that currently work. Level of
 support corresponds to ``S`` values in the ``MAINTAINERS`` file.
 
-.. list-table::
-   :widths: 10 10 10
-   :header-rows: 1
-
-   * - Architecture
-     - Level of support
-     - Constraints
-   * - ``arm``
-     - Maintained
-     - ``armv6`` and compatible only, ``RUST_OPT_LEVEL >= 2``
-   * - ``arm64``
-     - Maintained
-     - None
-   * - ``powerpc``
-     - Maintained
-     - ``ppc64le`` only, ``RUST_OPT_LEVEL < 2`` requires ``CONFIG_THREAD_SHIFT=15``
-   * - ``riscv``
-     - Maintained
-     - ``riscv64`` only
-   * - ``x86``
-     - Maintained
-     - ``x86_64`` only
+============  ================  ==============================================
+Architecture  Level of support  Constraints
+============  ================  ==============================================
+``arm``       Maintained        ``armv6`` and compatible only,
+                                ``RUST_OPT_LEVEL >= 2``.
+``arm64``     Maintained        None.
+``powerpc``   Maintained        ``ppc64le`` only, ``RUST_OPT_LEVEL < 2``
+                                requires ``CONFIG_THREAD_SHIFT=15``.
+``riscv``     Maintained        ``riscv64`` only.
+``x86``       Maintained        ``x86_64`` only.
+============  ================  ==============================================