manuals: replace hyphens with em dashes

Fix some hyphens being improperly used as em dashes.
See https://www.grammarly.com/blog/hyphens-and-dashes/

Using em dashes may also allow Sphinx to hyphenate
and break lines in the best way.

Note that the first character after an em dash not
supposed to be capitalized, unless a specific
rule applies, typically when what follows is a proper noun.

Fix a few misuses of parentheses in following text.

(From yocto-docs rev: 5918f019f63f6e820b1168f4cc001faa1d1cdc6f)

Signed-off-by: Michael Opdenacker <michael.opdenacker@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

documentation/ref-manual/classes.rst

@@ -108,18 +108,18 @@ support is either not present or is broken.
 It's useful to have some idea of how the tasks defined by the
 ``autotools*`` classes work and what they do behind the scenes.
 
--  :ref:`ref-tasks-configure` - Regenerates the
+-  :ref:`ref-tasks-configure` --- regenerates the
    configure script (using ``autoreconf``) and then launches it with a
    standard set of arguments used during cross-compilation. You can pass
    additional parameters to ``configure`` through the :term:`EXTRA_OECONF`
    or :term:`PACKAGECONFIG_CONFARGS`
    variables.
 
--  :ref:`ref-tasks-compile` - Runs ``make`` with
+-  :ref:`ref-tasks-compile` --- runs ``make`` with
    arguments that specify the compiler and linker. You can pass
    additional arguments through the :term:`EXTRA_OEMAKE` variable.
 
--  :ref:`ref-tasks-install` - Runs ``make install`` and
+-  :ref:`ref-tasks-install` --- runs ``make install`` and
    passes in ``${``\ :term:`D`\ ``}`` as ``DESTDIR``.
 
 .. _ref-classes-base: