fixes typos (#163)

* fixes typos

line 86: directly follow -> directly followed 
line 142: removes "it"
line 175: stored -> store
line 191: is -> are - adds comma before etc

* Update pages/en/developer/assemblyscript-api.mdx

Co-authored-by: Benoît Rouleau <benoit.rouleau@icloud.com>

Co-authored-by: Benoît Rouleau <benoit.rouleau@icloud.com>

Author: i-am-sam-codes

pages/en/developing/assemblyscript-api.mdx

@@ -83,7 +83,7 @@ _Operators_
 
 - `equals(y: ByteArray): bool` – can be written as `x == y`.
 - `concat(other: ByteArray) : ByteArray` - return a new `ByteArray` consisting of `this` directly followed by `other`
-- `concatI32(other: i32) : ByteArray` - return a new `ByteArray` consisting of `this` directly follow by the byte representation of `other`
+- `concatI32(other: i32) : ByteArray` - return a new `ByteArray` consisting of `this` directly followed by the byte representation of `other`
 
 #### BigDecimal
 
@@ -139,7 +139,7 @@ _Construction_
 
 - `x.toHex(): string` – turns `BigInt` into a string of hexadecimal characters.
 - `x.toString(): string` – turns `BigInt` into a decimal number string.
-- `x.toI32(): i32` – returns the `BigInt` as an `i32`; fails if it the value does not fit into `i32`. It's a good idea to first check `x.isI32()`.
+- `x.toI32(): i32` – returns the `BigInt` as an `i32`; fails if the value does not fit into `i32`. It's a good idea to first check `x.isI32()`.
 - `x.toBigDecimal(): BigDecimal` - converts into a decimal with no fractional part.
 
 _Math_
@@ -172,7 +172,7 @@ _Math_
 import { TypedMap } from '@graphprotocol/graph-ts'
 ```
 
-`TypedMap` can be used to stored key-value pairs. See [this example](https://github.com/graphprotocol/aragon-subgraph/blob/29dd38680c5e5104d9fdc2f90e740298c67e4a31/individual-dao-subgraph/mappings/constants.ts#L51).
+`TypedMap` can be used to store key-value pairs. See [this example](https://github.com/graphprotocol/aragon-subgraph/blob/29dd38680c5e5104d9fdc2f90e740298c67e4a31/individual-dao-subgraph/mappings/constants.ts#L51).
 
 The `TypedMap` class has the following API:
 
@@ -188,7 +188,7 @@ The `TypedMap` class has the following API:
 import { Bytes } from '@graphprotocol/graph-ts'
 ```
 
-`Bytes` is used to represent arbitrary-length arrays of bytes. This includes Ethereum values of type `bytes`, `bytes32` etc.
+`Bytes` is used to represent arbitrary-length arrays of bytes. This includes Ethereum values of type `bytes`, `bytes32`, etc.
 
 The `Bytes` class extends AssemblyScript's [Uint8Array](https://github.com/AssemblyScript/assemblyscript/blob/3b1852bc376ae799d9ebca888e6413afac7b572f/std/assembly/typedarray.ts#L64) and this supports all the `Uint8Array` functionality, plus the following new methods: