Undocument 'global' stuff

Author: Sainan

docs/Compatibility.md

@@ -49,15 +49,6 @@ So, writing a portable script that only makes use of Pluto 0.8.0's keywords requ
 pluto_use "0.8.0"
 ```
 
-This feature also supports quick encompassing of optional keywords. So, instead of:
-```pluto
-pluto_use "0.8.0", global
-```
-You can use a '+' after the version number to also enable all of the optional keywords. As of 0.9.0, the only optional keyword is `global`:
-```pluto
-pluto_use "0.9.0+" -- The same as pluto_use "0.9.0", global
-```
-
 For module developers and scripts which may be used in future versions of Pluto, we recommend you use `pluto_use` for two reasons:
 - **Portability.** This will override the compatibility mode settings compiled into Pluto so your script will be parsed identically in all Pluto environments.
 - **Proactive compatibility.** Any keywords added by future versions of Pluto will also be put in compatibility mode by these statements, so in the off-chance your script uses a future reserved keyword as a variable name, it would still parse as you intended when you wrote it.

docs/New Features/Compiler Warnings.md

@@ -191,32 +191,6 @@ switch a do
 end
 ```
 
-### implicit-global
-This is raised when a global is declared without an explicit prefix, such as the optional `global` keyword:
-```pluto showLineNumbers
-pluto_use global
-a = 1
-```
-```
-file.pluto:2: warning: implicit global creation [implicit-global]
-    2 | a = 1
-      | ^^^^^ here: prefix this with '_G.' or 'global' to be explicit
-```
-
-Examples of code that does not raise this warning:
-```pluto
-pluto_use global
-global a = 1
-a = 2
-```
-```pluto
--- @pluto_warnings enable-implicit-global
-_G.a = 1
-a = 2
-```
-
-This warning type is enabled via `pluto_use global` or [compile-time configuration](#compile-time-configuration).
-
 ### discarded-return
 This is raised when the return value of a function declared `<nodiscard>` was discarded. See [Nodiscard Functions](<Nodiscard Functions>).
 ```pluto showLineNumbers