Add documentation for cbi-tree options

Signed-off-by: John Pennycook <john.pennycook@intel.com>

Author: Pennycook

docs/source/cmd.rst

@@ -43,3 +43,41 @@ Command Line Interface
     Include the specified platform in the analysis.
     May be specified multiple times.
     If not specified, all platforms will be included.
+
+Tree Tool
+---------
+
+The tree tool generates a visualization of the code base where each file and
+directory is annotated with information about platform usage and coverage.
+
+.. code-block:: text
+
+    cbi-tree [-h] [--version] [-x <pattern>] [-p <platform>] [--prune] [-L <level>] <analysis-file>
+
+**positional arguments:**
+
+``analysis-file``
+    TOML file describing the analysis to be performed, including the codebase and platform descriptions.
+
+**options:**
+
+``-h, --help``
+    Display help message and exit.
+
+``--version``
+    Display version information and exit.
+
+``-x <pattern>, --exclude <pattern>``
+    Exclude files matching this pattern from the code base.
+    May be specified multiple times.
+
+``-p <platform>, --platform <platform>``
+    Include the specified platform in the analysis.
+    May be specified multiple times.
+    If not specified, all platforms will be included.
+
+``--prune``
+    Prune unused files from the tree.
+
+``-L <level>, --levels <level>``
+    Print only the specified number of levels.