osu!catch RC Cleanup

[ascendancelol]

Adjusts definitions, changes some too-old terminology, removes redundant rules, and updates some new stuff based on discussion

[osuZiRoX]

From https://osu.ppy.sh/community/forums/topics/938018

[cl8n]

some of these comments are about things u didnt actually change in this PR but w/e

[cl8n]

for commit messages and PR titles describe your changes in present tense, for example instead of "osu!catch RC Cleanup" it should be "Clean up osu!catch RC"

not that important but this is good git practice

[ascendancelol]

did more stuff, should be ok now

[ascendancelol]

what an adventure

[Joehuu]

Please don't use version numbering on commit titles next time. The commit description "fixed more bold stuff in expert guidelines" should've been the commit title instead and have an imperative mood (Fix).

[ascendancelol]

it was more for me to keep track of what was fixed bcs im bad at github but if its a serious problem then np lol

[pishifat]

minor thing, but #ms and # ms are used interchangeably. should stick with one format throughout the article. same for bpm/BPM capitalization/spacing

[JBHyperion]

minor thing, but #ms and # ms are used interchangeably. should stick with one format throughout the article. same for bpm/BPM capitalization/spacing

Units should have a space before them (so e.g. "250 ms"), and since BPM is an acronym, it should be capitalised.