[Docs] Added llvm-reduce docs in CommandGuide

[aabhinavg]

Summary

[Docs] Added llvm-reduce docs in CommandGuide

[aabhinavg]

Done minor changes

[aabhinavg]

.

[arsenm]

LGTM. We also have a how to file a bug using bugpoint as an example which should update to use llvm-reduce

llvm/docs/CommandGuide/index.rst

.. toctree::
    llvm-link
    llvm-lipo
    llvm-mc
    llvm-mca
    llvm-opt-report
    llvm-otool
    llvm-profdata
    llvm-readobj
+   llvm-reduce
    llvm-stress
    llvm-symbolizer
    opt
 
 GNU binutils replacements
 ~~~~~~~~~~~~~~~~~~~~~~~~~
 
 .. toctree::

llvm/docs/CommandGuide/llvm-reduce.rst

+llvm-reduce - LLVM automatic testcase reducer.
+==============================================
+
+.. program:: llvm-reduce
+
+SYNOPSIS
+--------
+
+:program:`llvm-reduce` [*options*] [*input...*]
+
+DESCRIPTION
+-----------
+
+The :program:`llvm-reduce` tool project that can be used for reducing the size of LLVM test cases.
+It works by removing redundant or unnecessary code from LLVM test cases while still preserving 
+their ability to detect bugs.
+
+If ``input`` is "``-``", :program:`llvm-reduce` reads from standard
+input. Otherwise, it will read from the specified ``filenames``.
+
+LLVM-Reduce is a useful tool for reducing the size and 
+complexity of LLVM test cases, making it easier to identify and debug issues in 
+the LLVM compiler infrastructure.
+
+GENERIC OPTIONS
+---------------
+
+
+.. option:: --help
+
+ Display available options (--help-hidden for more).
+
+.. option:: --abort-on-invalid-reduction
+
+ Abort if any reduction results in invalid IR
+
+.. option::--delta-passes=<string>  
+
+ Delta passes to run, separated by commas. By default, run all delta passes.
+
+
+.. option:: --in-place     
+
+ WARNING: This option will replace your input file with the reduced version!
+
+.. option:: --ir-passes=<string> 
+
+ A textual description of the pass pipeline, same as what's passed to `opt -passes`.
+
+.. option:: -j <uint>  
+
+ Maximum number of threads to use to process chunks. Set to 1 to disable parallelism.
+
+.. option::  --max-pass-iterations=<int>
+
+  Maximum number of times to run the full set of delta passes (default=5).
+
+.. option:: --mtriple=<string> 
+
+ Set the target triple.
+
+.. option:: --preserve-debug-environment
+
+ Don't disable features used for crash debugging (crash reports, llvm-symbolizer and core dumps)
+
+.. option:: --print-delta-passes  
+
+ Print list of delta passes, passable to --delta-passes as a comma separated liste.
+
+.. option:: --skip-delta-passes=<string>     
+
+ Delta passes to not run, separated by commas. By default, run all delta passes.
+
+.. option:: --starting-granularity-level=<uint>
+
+  Number of times to divide chunks prior to first test.
+
+  Note : Granularity refers to the level of detail at which the reduction process operates.
+  A lower granularity means that the reduction process operates at a more coarse-grained level,
+  while a higher granularity means that it operates at a more fine-grained level.
+
+.. option::  --test=<string> 
+
+ Name of the interesting-ness test to be run.
+
+.. option:: --test-arg=<string> 
+
+ Arguments passed onto the interesting-ness test.
+
+.. option:: --verbose    
+
+ Print extra debugging information.
+ 
+.. option::  --write-tmp-files-as-bitcode  
+
+ Always write temporary files as bitcode instead of textual IR.
+
+.. option:: -x={ir|mir}
+
+ Input language as ir or mir.
+
+EXIT STATUS
+------------
+
+:program:`llvm-reduce` returns 0 under normal operation. It returns a non-zero
+exit code if there were any errors.
+
+