Several small documentation fixes (#1259)

Author: Akuli

doc/classes.md

@@ -95,7 +95,7 @@ def main() -> int:
 ```
 
 The problem is that when we do `increment_y(p)`,
-we simply pass the 64 (or more) bytes of the instance `p` to the `increment_y()` function.
+we simply pass the 64 bits of the instance `p` to the `increment_y()` function.
 This is very similar to creating two variables `x` and `y` in the `main()` function:
 
 ```python

doc/enums.md

@@ -172,9 +172,6 @@ def main() -> int:
     return 0
 ```
 
-The purpose of the `assert` is to ensure that the `descriptions` array stays up to date
-when new operations are added.
-
 You can also convert integers to enums,
 but note that the result might not correspond with any member of the enum.
 For example:

doc/keywords.md

@@ -459,8 +459,7 @@ def main() -> int:
 Note that unlike in Python,
 you don't need to use `global` inside a function to modify the global variable.
 
-By default, global variables are always initialized to zero memory,
-and it is not possible to specify any other initializing.
+By default, global variables are always initialized to zero memory.
 For example, numbers are initialized to zero, booleans are initialized to `False` and pointers are initialized to `NULL`.
 It is possible to specify a different initial value: