Updated height maths and documentation

[pyandell99]

• Changed 2*mean_height to eff_detection_height in obs_flux.
• Added notes to a few places about using the max rsh as the effective detection height and desktop truncating the observations.
• Updated the vignettes to reflect this

[LucindaRoberts]

I have made some vignette changes here

Stochastic:
~/DEV_Symbolix/CRMC_CollisionRiskModelCollection/collision/LR_effectiveHeightCalcs/simple-simulation-example.Rmd

Deterministic:
~/DEV_Symbolix/CRMC_CollisionRiskModelCollection/collision/LR_effectiveHeightCalcs/deterministic-example.Rmd

Notes on changes on card : https://app.shortcut.com/symbolix/story/66050/sym-crmd-side-by-side-comparison-of-twte-model-modified-in-sprint

[techisdead]

Have reviewed. Vignettes updated including some additional edits by me and @LucindaRoberts. Checks pass, tests pass, docs re-doc-ed. I've updated new and bumped this to a 1.1.9000 dev version because we have a couple of other updates to make then we can bump the release