[enhancement] <BLANKLINE> is not handled correctly in docs

Examples in documentation (both stable and latest) display a ton of <BLANKLINE>

Search results of <BLANKLINE>:

• https://docs.chainer.org/en/stable/search.html?q=<BLANKLINE>&check_keywords=yes&area=default
• https://docs.chainer.org/en/latest/search.html?q=<BLANKLINE>&check_keywords=yes&area=default

One example is depth2space.

>>> X = np.arange(24).reshape(1, 4, 2, 3).astype(np.float32)
>>> X.shape
(1, 4, 2, 3)
>>> X
array([[[[ 0.,  1.,  2.],
         [ 3.,  4.,  5.]],
<BLANKLINE>
        [[ 6.,  7.,  8.],
         [ 9., 10., 11.]],
<BLANKLINE>
        [[12., 13., 14.],
         [15., 16., 17.]],
<BLANKLINE>
        [[18., 19., 20.],
         [21., 22., 23.]]]], dtype=float32)
>>> y = F.depth2space(X, 2)
>>> y.shape
(1, 1, 4, 6)
>>> y.array
array([[[[ 0.,  6.,  1.,  7.,  2.,  8.],
         [12., 18., 13., 19., 14., 20.],
         [ 3.,  9.,  4., 10.,  5., 11.],
         [15., 21., 16., 22., 17., 23.]]]], dtype=float32)

[kmaehashi]

It seems spec of Sphinx (?) has been changed at some point. It was OK in v4 docs. https://docs.chainer.org/en/v4.4.0/reference/generated/chainer.functions.get_item.html?highlight=blankline

[toslunar]

It seems fixed from the docs for Chainer v7.0.0b4.