fix typos and grammar in docs/manual/schema (#754)

docs/graphql/manual/schema/custom-resolvers.rst

@@ -6,7 +6,7 @@ Hasura GraphQL engine provides instant GraphQL APIs over the tables and views of
 auto-generating the CRUD resolvers. However, sometimes you might have to write custom resolvers to capture business
 logic that is unrelated to the database.
 
-We have setup `this boilerplate project <https://github.com/hasura/graphql-engine/tree/master/community/boilerplates/custom-resolvers>`_
+We have set up `this boilerplate project <https://github.com/hasura/graphql-engine/tree/master/community/boilerplates/custom-resolvers>`_
 illustrating how to write your own custom GraphQL resolvers and merge them with the Hasura GraphQL engine's resolvers.
 
 Follow the boilerplate's ``README.md`` for detailed instructions.

docs/graphql/manual/schema/default-values.rst

@@ -4,7 +4,7 @@ Setting default values for fields
 Let's say you want certain fields to have their values set automatically by Postgres if
 not explicitly passed. For example, an auto-incrementing id, a created_at timestamp, etc.
 
-We can achieve this by setting a default value for the field which could either be a fixed value or a simple sql
+We can achieve this by setting a default value for the field which could either be a fixed value or a simple SQL
 function.
 
 **Example:** Say we have a field ``created_at`` in a table ``article``  which we would want to be set to the current

docs/graphql/manual/schema/how-it-works.rst

@@ -32,7 +32,7 @@ mutations.
 Relationships or Connections
 ----------------------------
 
-Between one table/view and another table/view you can tell Hasura GraphQL engine to create a relationship or a
+Between one table/view and another table/view, you can tell Hasura GraphQL engine to create a relationship or a
 connection between
 their 2 nodes in a graph, using a particular column as a link. Often, you have foreign-key constraints that
 indicate a relationship and you can tell Hasura GraphQL engine to use that foreign-key constraint to create a

docs/graphql/manual/schema/index.rst

@@ -4,7 +4,7 @@ Schema
 Hasura GraphQL engine automatically generates your GraphQL schema and resolvers based on your tables/views
 in Postgres. **You don't need to write a GraphQL schema or resolvers.**
 
-The Hasura console gives you UI tools that speed up your data-modelling process or working with your existing database.
+The Hasura console gives you UI tools that speed up your data-modeling process, or working with your existing database.
 The console also automatically generates migrations or metadata files that you can edit directly and check into your
 version control.
 

docs/graphql/manual/schema/relationships/index.rst

@@ -35,7 +35,7 @@ Here are examples to create relationships using the two methods:
 
     .. image:: ../../../../img/graphql/manual/schema/add-foreign-key.png
 
-    **2) Create object relationship**
+    **2) Create an object relationship**
 
     Each article has one author. This is an ``object relationship``. The console
     infers this using the foreign-key and recommends the potential relationship in the ``Relationships`` tab
@@ -94,7 +94,7 @@ Here are examples to create relationships using the two methods:
           }
         }
 
-    **3) Create array relationship**
+    **3) Create an array relationship**
 
     An author can write multiple articles. This is an ``array relationship``.
 

docs/graphql/manual/schema/schema-stitching.rst

@@ -90,7 +90,7 @@ The GraphQL query to fetch this weather information would look like:
 
 Explore this API on `Apollo LaunchPad <https://launchpad.graphql.com/nxw8w0z9q7>`_.
 
-Note the usage of ``city_name`` as an argument for ``cityWeather`` query. Using this we can extend our original
+Note the usage of ``city_name`` as an argument for the ``cityWeather`` query. Using this we can extend our original
 Postgres's ``person`` schema to include weather information based on the ``city`` column of the person table.
 
 .. code-block:: graphql
@@ -102,7 +102,7 @@ Postgres's ``person`` schema to include weather information based on the ``city`
 We have extended the type person to have one more field called ``city_weather``. This will resolve to the weather
 schema defined above and the respective resolver will return appropriate data.
 
-The source code for the custom resolver can be found on github - `graphql-schema-stitching-demo
+The source code for the custom resolver can be found on GitHub - `graphql-schema-stitching-demo
 <https://github.com/hasura/graphql-schema-stitching-demo>`_. Note the usage of ``mergeSchemas``, a
 ``graphql-tools`` utility that enables schema stitching.