DRAFT: Improvements to FM blog post (#5)

* fix: Figure 10 is now correctly showing the conditional paths for G2G example

* fix: updated citation

* added table of contents and made headings a bit nicer

* fixed reference to different formulations of NF formulation

* added citations as suggested by feedback

* sorted references

* added description on setup for one of the figures

* updated figure numbers

* use `text-align: center` for captions

* added missing word

* independant -> independent

* added proper attribution of figures taken from Albergo et al. (2023)

* added cond path splot for G2G example

* further improvements to OT section + additional plots + specific
definition of RectFlow example

* updated figure numbers

* improved explanation of sampling vs cmoputing expectation of OT coupling

* minor correction to note on OT

* renamed references to Continuity Equation with Transport Equation and
fixed some colouring issues

* fixed minor mathjax issue

* added a "commutation diagram" to illustrate relation of marginal and
conditional flows / vector fields

* minor improvements to one figure

* another figure number update