[Docs] Added tools to directory structure (#4504)

* Add unlisted tools in directory structure

* Add description to tools in directory structure

* [docs] Improved descriptions for tools list

Improved descriptions for tools list in the structure of Compiler source code organization

Co-authored-by: Fabian Ruffy <5960321+fruffy@users.noreply.github.com>

* [docs] Improved descriptions for tools list

Improved descriptions "ci-ptf" and "debian-build" in the structure of Compiler source code organization

Co-authored-by: Fabian Ruffy <5960321+fruffy@users.noreply.github.com>

---------

Co-authored-by: Fabian Ruffy <5960321+fruffy@users.noreply.github.com>

docs/README.md

@@ -35,9 +35,14 @@ p4c
 ├── test                      -- test code
 │   └── gtest                 -- unit test code written using gtest
 ├── tools                     -- external programs used in the build/test process
+│   ├── ci-ptf                -- scripts to run PSA PTF tests
+│   ├── debian-build          -- resources and scripts for creating Ubuntu (or Debian) packages
 │   ├── driver                -- p4c compiler driver: a script that invokes various compilers
-│   ├── stf                   -- Python code to parse STF files (used for testing P4 programs)
-|   └── ir-generator          -- code for the IR C++ class hierarchy generator
+│   ├── hooks                 -- useful git hooks for development
+|   ├── ir-generator          -- code to generate the P4C IR from .def files
+│   ├── iwyu_mappings         -- mappings used by the Include What You Use (IWYU) tool for analyzing #include directives in C and C++ source files
+│   ├── ptf                   -- utilities for the Packet Test Framework (PTF)
+│   └── stf                   -- utilities for the Simple Test Framework (STF)
 └── testdata                  -- test inputs and reference outputs
     ├── p4_16_samples         -- P4_16 input test programs
     ├── p4_16_errors          -- P4_16 negative input test programs