Major repository cleanup and enhancement

- Reorganize documentation: moved old docs to docs/ directory
- Add comprehensive README.md with build options and usage guide
- Add detailed CONTRIBUTING.md with help content management guide
- Create Makefile for automated building and testing
- Add Dockerfile.scratch for building from Ubuntu 20.04 base
- Enhance all Dockerfiles with PowerShell + PSScriptAnalyzer
- Add modern shells: zsh (with plugins) and fish (with config)
- Add modern CLI tools: fd-find, ripgrep, fzf
- Create comprehensive help system with cheat/TLDR/fish completions
- Add helper scripts for help content management and coverage checking
- Fix Dockerfile.remnux script references
- Support three build variants: upstream (REMnux), scratch (Ubuntu), kali

Build options:
  - make build-upstream: Fast, uses REMnux upstream (recommended)
  - make build-scratch: Full control, builds from Ubuntu 20.04
  - make build-kali: Legacy Kali Linux base

Features:
  - PowerShell with PSScriptAnalyzer module
  - Modern shells (zsh, fish) with custom configurations
  - Enhanced help system (cheat sheets, TLDR pages, fish completions)
  - Help coverage checking and bulk import tools
  - Comprehensive documentation for users and contributors

Dockerfile

@@ -11,6 +11,8 @@ RUN apt-get update && apt-get install -y \
   catdoc \
   docx2txt \
   exiftool \
+  fd-find \
+  fish \
   git \
   imagemagick \
   libboost-python-dev \
@@ -28,13 +30,18 @@ RUN apt-get update && apt-get install -y \
   pev \
   pkg-config \
   pipx \
+  powershell \
   python3 \
   python3-lxml \
   python3-pip \
+  ripgrep \
   ruby \
   unrtf \
   unzip \
   wget \
+  zsh \
+  zsh-autosuggestions \
+  zsh-syntax-highlighting \
   ; \
   rm -rf /var/lib/apt/lists/*
 
@@ -53,11 +60,22 @@ RUN gem install origami
 
 RUN sed -i '/PDF/s/"none"/"read|write"/' /etc/ImageMagick-6/policy.xml
 
+# PowerShell: Install PSScriptAnalyzer module
+RUN pwsh -NoProfile -Command "Install-Module -Name PSScriptAnalyzer -Force"
+
 ENV PATH="${PATH}:/opt/didierstevenssuite/:/opt/pypy2.7-v7.3.5-linux64/bin"
 ADD files/README /opt/README
 ADD files/command_help /opt/command_help
 RUN echo 'cat /opt/README' >> /etc/bash.bashrc
 
+# Add shell configurations
+ADD files/zshrc /etc/zsh/zshrc
+ADD files/fish_config.fish /etc/fish/conf.d/remnux.fish
+
+# Add helper scripts for cheat sheet management
+ADD scripts/add-tool-cheats.sh /tmp/add-tool-cheats.sh
+RUN chmod +x /tmp/add-tool-cheats.sh && /tmp/add-tool-cheats.sh && rm /tmp/add-tool-cheats.sh
+
 
 ###  VIPERMONKEY
 ## install pypy