docs: admin-guide: Clarify sentences

Changes to make the text more formal and organized. The reasons are now cited and described at the same time.
Minor grammatical problems have also been fixed.
Signed-off-by: Cristian Souza <cristianmsbr@gmail.com>
Link: https://lore.kernel.org/r/20200411010201.GA22706@darkstarSigned-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/admin-guide/init.rst

-Explaining the dreaded "No init found." boot hang message
+Explaining the "No working init found." boot hang message
 =========================================================
+:Authors: Andreas Mohr <andi at lisas period de>
+          Cristian Souza <cristianmsbr at gmail period com>
 
-OK, so you've got this pretty unintuitive message (currently located
-in init/main.c) and are wondering what the H*** went wrong.
-Some high-level reasons for failure (listed roughly in order of execution)
-to load the init binary are:
-
-A) Unable to mount root FS
-B) init binary doesn't exist on rootfs
-C) broken console device
-D) binary exists but dependencies not available
-E) binary cannot be loaded
-
-Detailed explanations:
-
-A) Set "debug" kernel parameter (in bootloader config file or CONFIG_CMDLINE)
-   to get more detailed kernel messages.
-B) make sure you have the correct root FS type
-   (and ``root=`` kernel parameter points to the correct partition),
-   required drivers such as storage hardware (such as SCSI or USB!)
-   and filesystem (ext3, jffs2 etc.) are builtin (alternatively as modules,
-   to be pre-loaded by an initrd)
-C) Possibly a conflict in ``console= setup`` --> initial console unavailable.
-   E.g. some serial consoles are unreliable due to serial IRQ issues (e.g.
-   missing interrupt-based configuration).
+This document provides some high-level reasons for failure
+(listed roughly in order of execution) to load the init binary.
+
+1) **Unable to mount root FS**: Set "debug" kernel parameter (in bootloader
+   config file or CONFIG_CMDLINE) to get more detailed kernel messages.
+
+2) **init binary doesn't exist on rootfs**: Make sure you have the correct
+   root FS type (and ``root=`` kernel parameter points to the correct
+   partition), required drivers such as storage hardware (such as SCSI or
+   USB!) and filesystem (ext3, jffs2, etc.) are builtin (alternatively as
+   modules, to be pre-loaded by an initrd).
+
+3) **Broken console device**: Possibly a conflict in ``console= setup``
+   --> initial console unavailable. E.g. some serial consoles are unreliable
+   due to serial IRQ issues (e.g. missing interrupt-based configuration).
    Try using a different ``console= device`` or e.g. ``netconsole=``.
-D) e.g. required library dependencies of the init binary such as
-   ``/lib/ld-linux.so.2`` missing or broken. Use
-   ``readelf -d <INIT>|grep NEEDED`` to find out which libraries are required.
-E) make sure the binary's architecture matches your hardware.
-   E.g. i386 vs. x86_64 mismatch, or trying to load x86 on ARM hardware.
-   In case you tried loading a non-binary file here (shell script?),
-   you should make sure that the script specifies an interpreter in its shebang
-   header line (``#!/...``) that is fully working (including its library
-   dependencies). And before tackling scripts, better first test a simple
-   non-script binary such as ``/bin/sh`` and confirm its successful execution.
-   To find out more, add code ``to init/main.c`` to display kernel_execve()s
-   return values.
+
+4) **Binary exists but dependencies not available**: E.g. required library
+   dependencies of the init binary such as ``/lib/ld-linux.so.2`` missing or
+   broken. Use ``readelf -d <INIT>|grep NEEDED`` to find out which libraries
+   are required.
+
+5) **Binary cannot be loaded**: Make sure the binary's architecture matches
+   your hardware. E.g. i386 vs. x86_64 mismatch, or trying to load x86 on ARM
+   hardware. In case you tried loading a non-binary file here (shell script?),
+   you should make sure that the script specifies an interpreter in its
+   shebang header line (``#!/...``) that is fully working (including its
+   library dependencies). And before tackling scripts, better first test a
+   simple non-script binary such as ``/bin/sh`` and confirm its successful
+   execution. To find out more, add code ``to init/main.c`` to display
+   kernel_execve()s return values.
 
 Please extend this explanation whenever you find new failure causes
 (after all loading the init binary is a CRITICAL and hard transition step
-which needs to be made as painless as possible), then submit patch to LKML.
+which needs to be made as painless as possible), then submit a patch to LKML.
 Further TODOs:
 
 - Implement the various ``run_init_process()`` invocations via a struct array
   which can then store the ``kernel_execve()`` result value and on failure
   log it all by iterating over **all** results (very important usability fix).
-- try to make the implementation itself more helpful in general,
-  e.g. by providing additional error messages at affected places.
+- Try to make the implementation itself more helpful in general, e.g. by
+  providing additional error messages at affected places.
 
-Andreas Mohr <andi at lisas period de>