manuals: suppress excess use of "following" word

To simplify the style, replace "Following is" and "Following are"
by "here is" and "here are", sounding more natural.

In some cases, also go further by simplifying "Here are/is xxx"
by "xxx are/is" when the "are" or "is" are not two far at
the end of the sentence.

In some cases too, completely remove the sentence, when
it's redundant with the preceding title.

(From yocto-docs rev: 2539f1b9cbf9bdd40eff93c6522dc76133debed7)

Signed-off-by: Michael Opdenacker <michael.opdenacker@bootlin.com>
CC: Daniel Ammann <daniel.ammann@bytesatwork.ch>
Signed-off-by: Steve Sakoman <steve@sakoman.com>

documentation/migration-guides/migration-2.4.rst

@@ -89,8 +89,6 @@ occurred:
 Removed Recipes
 ---------------
 
-The following recipes have been removed:
-
 -  ``acpitests``: This recipe is not maintained.
 
 -  ``autogen-native``: No longer required by Grub, oe-core, or
@@ -213,8 +211,6 @@ recipes you might have. This will avoid breakage in post 2.4 releases.
 Package QA Changes
 ------------------
 
-The following package QA changes took place:
-
 -  The "unsafe-references-in-scripts" QA check has been removed.
 
 -  If you refer to ``${COREBASE}/LICENSE`` within
@@ -229,8 +225,6 @@ The following package QA changes took place:
 ``README`` File Changes
 -----------------------
 
-The following are changes to ``README`` files:
-
 -  The main Poky ``README`` file has been moved to the ``meta-poky``
    layer and has been renamed ``README.poky``. A symlink has been
    created so that references to the old location work.
@@ -246,8 +240,6 @@ The following are changes to ``README`` files:
 Miscellaneous Changes
 ---------------------
 
-The following are additional changes:
-
 -  The ``ROOTFS_PKGMANAGE_BOOTSTRAP`` variable and any references to it
    have been removed. You should remove this variable from any custom
    recipes.