fix typos in lgssm_learning.ipynb

[partev]

"work with simulate noisy data" -> "work with simulated noisy data" $\mathrm{N}(F z_t, Q)$ -> $\mathcal{N}(F z_t, Q)$ $\mathrm{N}(H z_t, R)$ -> $\mathcal{N}(H z_t, R)$ $\mathbb{R}^10$ -> $\mathbb{R}^{10}$ "paraemeters" -> "parameters" "freeing the dynamics matrix" -> "freezing the dynamics matrix"