Improve CLI docs (#1404)

* Improve CLI docs

* Fixed all the typos (hopefully).
* Improved the bad English. This encompasses grammar, vocabulary, generally awkward phrases, etc. The result is easier to read and understand, and in some cases shorter.
* Made some formatting improvements. This includes making formatting more consistent, but I changed some of it to be better, at least in my opinion.
* Removed certain unnecessities, the biggest one being the commands documentation. I think this is unnecessary because of the `dx --help` command. It also needs to be updated every time a command gets added/updated/removed. It doesn't really provide much extra insight than `dx --help`.
* Improved plugin documentation. I added a warning to ignore all of it, which is ironic, but the fact is that plugins are probably going to change. But by the time I learned that, I already made some changes to the plugin docs. This includes a better guide on how to get started (although still bad since the plugin system is too messy), and some general changes like the aforementioned English or formatting.
* And more. I can't list it all, but I didn't use any destructive changes. The content might be reformatted (to be shorter or easier to understand), but the meaning isn't lost.

* Fix grammar in packages/cli/docs/src/creating.md

Co-authored-by: Evan Simkowitz <esimkowitz@users.noreply.github.com>

* Update README.md

* Change config example

---------

Co-authored-by: Evan Simkowitz <esimkowitz@users.noreply.github.com>

packages/cli/docs/src/plugin/interface/os.md

@@ -1,10 +1,10 @@
 # OS Functions
 
-> you can use OS functions to get some system information
+OS functions are for getting system information.
 
-### current_platform() -> string ("windows" | "macos" | "linux")
+### `current_platform() -> string ("windows" | "macos" | "linux")`
 
-This function can help you get system & platform type:
+Get the current OS platform.
 
 ```lua
 local platform = plugin.os.current_platform()