ci(doc-linter): fix RST code-block exit on short dedented lines

The dedent check inside `handle_file_action()` was

    if in_rst_codeblock:
        if len(line) > rst_codeblock_indent and not line[rst_codeblock_indent].isspace():
            in_rst_codeblock = False

This worked only when the next line was at least
`rst_codeblock_indent + 1` chars long — the indexing
`line[rst_codeblock_indent]` requires that. A short dedented
line (e.g., a single character at column 0 under a directive
indented at column 4) failed the length guard and `in_rst_codeblock`
stayed True. The block remained open longer than it should,
suppressing line-length checks on subsequent prose until either
EOF or the next `.. code-block::` reset the state.

Replace with a leading-whitespace-count check: on any non-blank
line, exit the block when leading-ws is <= the directive's
column. Blank lines don't reset the block context.

Test: a 3-line file with `.. code-block:: text` directive at col
0, one body line, a single `a` at col 0, then a 113-char line
at col 0. With the old logic the long line is still treated as
inside the code block and not flagged. With the new logic the
single-`a` dedent exits the block and the long line is flagged
as expected.

Tracked as items 6 and 12 of the rolling-side cleanup backlog
from PR #2014 / #2019 / #2020 reviews.

🤖 Generated by [robots](https://vyos.io)

(cherry picked from commit 6628b2901933f67568ba68617ee27c6f843c6dcf)

0 files changed, 0 insertions, 0 deletions