Sensor documentation

[oscgonfer]

Currently we have three places where sensor information is added:

1. Supported sensors page
2. Sensor knowledge
3. Guides for calibrating / using each sensor

For maintainability purposes, it would be great if we can do something similar to what we did in the mdef-docs for faculty and other content that can be processed by a macro.

Current proposal:

• We move sensors performance/knowledge toc item to a nav item
• We organise by:

- Sensors: brief explanation. Onboard and external. 
    - Air: brief explanation, supporting documents. Supported sensors summary with colors to distinguish onboard vs external.
        - CO2:  explanation of the metric, plus supported sensor cards (summary page)
            - Sensor 1,
            - Sensor 2...
        - PM:  explanation of the metric, plus supported sensor cards (summary page)
            - Sensor 1,
            - Sensor 2...
    - Water: brief explanation, supporting documents. Supported sensors summary with colors to distinguish onboard vs external.
        - pH: explanation of the metric, plus supported sensor cards (summary page)
            - Sensor 1,
            - Sensor 2...

An example is already found on the docs already: /hardware/sensors/air/co2/Sensirion_SCD30/

A good visual reference for this can be found on: https://blokas.io

TODO:

• Finalise frontmatter for each sensor @oscgonfer
• Adapt all sensors to same frontmatter schema @oscgonfer @peters-rebecca
• Work on the card design @peters-rebecca
• Add card views on each summary page @peters-rebecca
• Add descriptions to each level (main, field, metric) @oscgonfer @peters-rebecca
• Make sure images work @peters-rebecca