Update rangefinder documentation

[sensei-hacker]

User description

Summary

Updates docs/Rangefinder.md to reflect the current state of rangefinder support in INAV, removing outdated "experimental" labels and providing comprehensive configuration guidance.

Changes

• Clarify AGL definition: "altitude Above Ground Level (AGL), the distance to the ground directly beneath the aircraft"
• Update features section: Remove "very limited" language, add GPS-free navigation capability
• Expand hardware list: Add VL53L1X, US42, BENEWAKE, FAKE sensor types
• Add Surface mode section: Document terrain following for multirotors with configuration examples
• Add configuration section: CLI commands for setup and position estimation weights
• Add optical flow integration: Explain how rangefinder + optic flow enable GPS-free navigation
• Add troubleshooting guide: Common issues and solutions
• Add references: Link to wiki documentation

Testing

Documentation-only change - no code modifications.

Verified:

• Hardware list matches current sensor support in settings.yaml
• CLI commands match actual setting names
• Surface mode description matches code behavior (multirotors only)
• Wiki link is valid and points to newly created comprehensive guide

Documentation

This PR updates the technical documentation in docs/Rangefinder.md.

Related wiki documentation already merged:

• https://github.com/iNavFlight/inav/wiki/Optic-Flow-and-Rangefinder

Motivation

The existing documentation called rangefinder support "very limited" and labeled Surface mode as "experimental", which no longer reflects INAV's mature rangefinder capabilities after years of development and refinement.

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PR Type

Documentation

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Description

• Comprehensive update removing outdated "experimental" labels

• Reorganized hardware list with sensor categories and specifications

• Added Surface mode terrain following documentation for multirotors

• Included configuration examples and optical flow integration guide

• Added troubleshooting section and constraint documentation

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Diagram Walkthrough

flowchart LR
  A["Old Documentation<br/>Limited & Experimental"] -->|Remove outdated labels| B["Updated Features<br/>Landing, Terrain Following, GPS-free Nav"]
  C["Minimal Hardware List<br/>Few sensors listed"] -->|Reorganize & expand| D["Categorized Hardware<br/>ToF, Ultrasonic, Radar, Serial"]
  E["Basic Connections"] -->|Add configuration| F["Complete Setup Guide<br/>CLI commands & weights"]
  G["No Surface Mode Docs"] -->|Add section| H["Surface Mode Guide<br/>Multirotors only"]
  I["No Integration Info"] -->|Add section| J["Optical Flow Integration<br/>GPS-free position hold"]
  K["No Troubleshooting"] -->|Add section| L["Troubleshooting Guide<br/>Common issues & solutions"]

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File Walkthrough

Relevant files

Documentation

Rangefinder.md Complete rangefinder documentation overhaul with current features docs/Rangefinder.md Clarified AGL definition with explicit distance measurement explanation Removed "very limited" and "experimental" language throughout document Reorganized hardware section into categories: ToF Laser, Ultrasonic, Radar, Serial/External, and Development sensors Added VL53L1X, US42, BENEWAKE, and FAKE sensor types to hardware list Added comprehensive Surface mode section explaining terrain following for multirotors only Added Configuration section with CLI commands for sensor setup and position estimation weights Added Optical Flow Integration section explaining GPS-free navigation capability Added Troubleshooting guide covering common issues and solutions Added References section with wiki links Improved formatting with subsections and code blocks for CLI commands +139/-28

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[qodo-code-review]

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