Fix typo in readme (#845)

# Description

Please add an informative description that covers that changes made by
the pull request and link all relevant issues.

# All Promptflow Contribution checklist:
- [X] **The pull request does not introduce [breaking changes].**
- [ ] **CHANGELOG is updated for new features, bug fixes or other
significant changes.**
- [X] **I have read the [contribution guidelines](../CONTRIBUTING.md).**
- [X] **Create an issue and link to the pull request to get dedicated
review from promptflow team. Learn more: [suggested
workflow](../CONTRIBUTING.md#suggested-workflow).**

## General Guidelines and Best Practices
- [X] Title of the pull request is clear and informative.
- [ ] There are a small number of commits, each of which have an
informative message. This means that previously merged commits do not
appear in the history of the PR. For more information on cleaning up the
commits in your PR, [see this
page](https://github.com/Azure/azure-powershell/blob/master/documentation/development-docs/cleaning-up-commits.md).

### Testing Guidelines
- [X] Pull request includes test coverage for the included changes.

---------

Co-authored-by: minggu <[email protected]>

README.md

@@ -93,7 +93,7 @@ We also offer a VS Code extension (a flow designer) for an interactive flow deve
 
 You can install it from the <a href="https://marketplace.visualstudio.com/items?itemName=prompt-flow.prompt-flow">visualstudio marketplace</a>.
 
-#### Deep dive into flow development
+#### Deep delve into flow development
 
 [Getting Started with Prompt Flow](https://microsoft.github.io/promptflow/how-to-guides/quick-start.html): A step by step guidance to invoke your first flow run.
 

docs/how-to-guides/init-and-test-a-flow.md

@@ -46,8 +46,8 @@ Alternatively, you can use the "Create new flow" action on the Prompt flow pane
 
 Structure of flow folder:
 - **flow.dag.yaml**: The flow definition with inputs/outputs, nodes, tools and variants for authoring purpose.
-- **.promptflow/flow.tools.json**: It contains all package tools meta that references in `flow.dag.yaml`.
-- **Source code files (.py, .jinja2)**: User managed, the code scripts that references by tools.
+- **.promptflow/flow.tools.json**: It contains tools meta referenced in `flow.dag.yaml`.
+- **Source code files (.py, .jinja2)**: User managed, the code scripts referenced by tools.
 - **requirements.txt**: Python package dependencies for this flow.
 
 ![init_flow_folder](../media/how-to-guides/init-and-test-a-flow/flow_folder.png)

docs/how-to-guides/quick-start.md

@@ -36,7 +36,7 @@ pf -v
 
 ## Understand what's a flow
 
-A flow, represented as a YAML file, is a DAG of functions, which connected via input/output dependencies, and executed based on the topology by Prompt flow executor. See [Flows](../../concepts/concept-flows.md) for more details.
+A flow, represented as a YAML file, is a DAG of functions, which is connected via input/output dependencies, and executed based on the topology by Prompt flow executor. See [Flows](../../concepts/concept-flows.md) for more details.
 
 ### Get the flow sample
 
@@ -55,8 +55,8 @@ cd promptflow/examples/flows/standard/web-classification
 
 A flow directory is a directory that contains all contents of a flow. Structure of flow folder:
 - **flow.dag.yaml**: The flow definition with inputs/outputs, nodes, tools and variants for authoring purpose.
-- **.promptflow/flow.tools.json**: It contains all package tools meta that references in `flow.dag.yaml`.
-- **Source code files (.py, .jinja2)**: User managed, the code scripts that references by tools.
+- **.promptflow/flow.tools.json**: It contains tools meta referenced in `flow.dag.yaml`.
+- **Source code files (.py, .jinja2)**: User managed, the code scripts referenced by tools.
 - **requirements.txt**: Python package dependencies for this flow.
 
 
@@ -69,7 +69,7 @@ pip install -r requirements.txt
 ```
 
 ### Understand the flow yaml
-The entry file of a flow directory is [`flow.dag.yaml`](https://github.com/microsoft/promptflow/blob/main/examples/flows/standard/web-classification/flow.dag.yaml) which describes the `DAG(Directed Acyclic Graph)` of a flow. The flow dag of this sample likes below:
+The entry file of a flow directory is [`flow.dag.yaml`](https://github.com/microsoft/promptflow/blob/main/examples/flows/standard/web-classification/flow.dag.yaml) which describes the `DAG(Directed Acyclic Graph)` of a flow. Below is a sample of flow DAG:
 
 ![flow_dag](../media/how-to-guides/quick-start/flow_dag.png)