Fix a handful of grammatical errors (#182)

* Fix subject/verb agreement

Because the subject ("versions") is plural, the verb should be "adopt",
not "adopts".

* Fix typo

* Add missing word

* Add missing word

* Fix typo

* Fix article

* Fix word that should be plural

* Fix word that should be plural

* Fix word that should be singular

* Fix subject/verb agreement

* Fix word that should be singular

* Fix word that should be singular

Author: jasonrudolph

spec/Section 2 -- Language.md

@@ -936,5 +936,5 @@ of any input type.
 Directives can be used to describe additional information for fields, fragments,
 and operations.
 
-As future versions of GraphQL adopts new configurable execution capabilities,
+As future versions of GraphQL adopt new configurable execution capabilities,
 they may be exposed via directives.

spec/Section 3 -- Type System.md

@@ -124,7 +124,7 @@ these names must adhere to the behavior described below.
 
 #### Int
 
-The Int scalar type represents a signed 32-bit numeric non-fractional values.
+The Int scalar type represents a signed 32-bit numeric non-fractional value.
 Response formats that support a 32-bit integer or a number type should use
 that type to represent this scalar.
 
@@ -212,7 +212,7 @@ other input values must raise a query error indicating an incorrect type.
 #### ID
 
 The ID scalar type represents a unique identifier, often used to refetch an
-object or as key for a cache. The ID type is serialized in the same way as
+object or as the key for a cache. The ID type is serialized in the same way as
 a `String`; however, it is not intended to be human-readable. While it is
 often numeric, it should always serialize as a `String`.
 
@@ -256,7 +256,7 @@ type Person {
 ```
 
 Where `name` is a field that will yield a `String` value, and `age` is a field
-that will yield an `Int` value, and `picture` a field that will yield a
+that will yield an `Int` value, and `picture` is a field that will yield a
 `Url` value.
 
 A query of an object value must select at least one field. This selection of
@@ -537,7 +537,7 @@ of rules must be adhered to by every Object type in a GraphQL schema.
 ### Interfaces
 
 GraphQL Interfaces represent a list of named fields and their arguments. GraphQL
-object can then implement an interface, which guarantees that they will
+objects can then implement an interface, which guarantees that they will
 contain the specified fields.
 
 Fields on a GraphQL interface have the same rules as fields on a GraphQL object;
@@ -717,7 +717,7 @@ Unions are never valid inputs.
 
 Union types have the potential to be invalid if incorrectly defined.
 
-1. The member types of an Union type must all be Object base types;
+1. The member types of a Union type must all be Object base types;
    Scalar, Interface and Union types may not be member types of a Union.
    Similarly, wrapping types may not be member types of a Union.
 2. A Union type must define one or more member types.
@@ -827,7 +827,7 @@ exclamation mark is used to denote a field that uses a Non-Null type like this:
 
 **Result Coercion**
 
-In all of the above result coercion, {null} was considered a valid value.
+In all of the above result coercions, {null} was considered a valid value.
 To coerce the result of a Non-Null type, the coercion of the wrapped type
 should be performed. If that result was not {null}, then the result of coercing
 the Non-Null type is that result. If that result was {null}, then a field error

spec/Section 4 -- Introspection.md

@@ -63,7 +63,7 @@ would return
 ### Naming conventions
 
 Types and fields required by the GraphQL introspection system that are used in
-the same context as user-defined type and fields are prefixed with two
+the same context as user-defined types and fields are prefixed with two
 underscores. This in order to avoid naming collisions with user-defined GraphQL
 types.  Conversely, GraphQL type system authors must not define any types,
 fields, arguments, or any other type system artifact with two leading
@@ -252,7 +252,7 @@ Fields
 
 #### Union
 
-Unions are an abstract types where no common fields are declared. The possible
+Unions are an abstract type where no common fields are declared. The possible
 types of a union are explicitly listed out in `possibleTypes`. Types can be
 made parts of unions without modification of that type.
 
@@ -268,7 +268,7 @@ Fields
 
 #### Interface
 
-Interfaces is an abstract type where there are common fields declared. Any type
+Interfaces are an abstract type where there are common fields declared. Any type
 that implements an interface must define all the fields with names and types
 exactly matching. The implementations of this interface are explicitly listed
 out in `possibleTypes`.

spec/Section 5 -- Validation.md

@@ -99,7 +99,7 @@ type QueryRoot {
 
 ** Explanatory Text **
 
-Each named operation definitions must be unique within a document when referred
+Each named operation definition must be unique within a document when referred
 to by its name.
 
 For example the following document is valid:
@@ -319,7 +319,7 @@ SameResponseShape(fieldA, fieldB) :
 
 ** Explanatory Text **
 
-If multiple fields selections with the same response names are encountered
+If multiple field selections with the same response names are encountered
 during execution, the field and arguments to execute and the resulting value
 should be unambiguous. Therefore any two field selections which might both be
 encountered for the same object are only valid if they are equivalent.