[docs][llvm-readobj] Improve llvm-readobj documentation

There were a number of issues with the llvm-readobj documentation. The
following points were raised in https://bugs.llvm.org/show_bug.cgi?id=42255,
and have been fixed in this patch:

 1. The description section claimed "The tool and its output is
    primarily designed for use in FileCheck-based tests" which is not
    really the case any more.
 2. The documentation used single-dash long options for option names,
    but references in the help text to other options exclusively used
    double-dashes. Fixed by standardising on double-dashes for all
    long-form options.
 3. The majority of options available and in the help text were not
    present in the documentation. This patch adds them.
 4. Several aliases, both long and short, were missing, e.g. --relocs.

Additionally, this patch improves the documentation by:

 1. Splitting the options into categories based on the file format they
    are specific to.
 2. Updating the Exit Status section to correctly mention that errors
    lead to a non-zero exit code.
 3. Adding a See Also section referencing other similar LLVM tools.
 4. Improving/correcting some of the descriptions of options that did
    not quite match up with what llvm-readobj does.

Reviewed by: peter.smith, MaskRay, mtrent

Differential Revision: https://reviews.llvm.org/D63719

llvm-svn: 364306

0 files changed, 0 insertions, 0 deletions