Update eigenvalue page

[pascaladhikary]

• reorganize in slide order
• include finding eval/evec example, code snippet
• replace cost summary with cost/convergence table

[jlevine18]

this is a good start- see my comments. i'd also take a bit of a closer look at some of the power iteration section that we currently have and give a little more to help students build intuition- we ask a lot of questions about errors/convergence/advantage of normalization, which the notes are somewhat lacking in. i'd also add a couple graphical examples as well to show eigenvals/eigenvecs as deformation directions, and convergence during the steps of power iteration. i'd also look into moving some stuff around in the power-iteration section and making that the whole text is cohesive and reads well. feel free to do things a little differently- the most important goals are that the material contains everything someone might need to do hw/a quiz and that it reads well

[jlevine18]

also it's probably worth doing one last check to make sure that everything from the slides/videos is in here

[jlevine18]

looks good- thanks for your help

[devksingh4]

lgtm