[Feature request] Add new themes screenshots and examples

[george-gca]

Add screenshots and examples of the newly introduced themes in #135.
The new themes, from https://github.com/anuraghazra/github-readme-stats, are:

algolia
apprentice
aura_dark
aura
ayu_mirage
bear
blue_green
blueberry
buefy
calm
chartreuse_dark
city_lights
cobalt
cobalt2
codeSTACKr
darcula
dark
date_night
discord_old_blurple
flag_india
gotham
graywhite
great_gatsby
highcontrast
jolly
kacho_ga
maroongold
material_palenight
merko
midnight_purple
moltack
moonlight
nightowl
noctis_minimus
ocean_dark
omni
onedark
outrun
panda
prussian
react
rose_pine
shades_of_purple
slateorange
swift
synthwave
vision_friendly_dark
yeblu