Fix broken DagRunApi.md docs link (filename casing)

The top-level README links to docs/DagRunApi.md but the file on disk was
docs/DAGRunApi.md, so the link 404s on case-sensitive filesystems and does
not match the openapi-generator canonical output. The wrong casing is a
2.x-era leftover that survived regenerations because case-only renames are
dropped on case-insensitive (macOS) filesystems where the client is built.

Rename to canonical DagRunApi.md and update the two remaining references to
the old path.

Author: potiuk

airflow_client/.openapi-generator/FILES

@@ -169,7 +169,7 @@ docs/DAGCollectionAllOf.md
 docs/DAGDetail.md
 docs/DAGDetailAllOf.md
 docs/DAGRun.md
-docs/DAGRunApi.md
+docs/DagRunApi.md
 docs/DAGRunCollection.md
 docs/DAGRunCollectionAllOf.md
 docs/DagProcessorStatus.md

airflow_client/README.md

@@ -338,15 +338,15 @@ Class | Method | HTTP request | Description
 *DAGApi* | [**patch_dags**](docs/DAGApi.md#patch_dags) | **PATCH** /dags | Update DAGs
 *DAGApi* | [**post_clear_task_instances**](docs/DAGApi.md#post_clear_task_instances) | **POST** /dags/{dag_id}/clearTaskInstances | Clear a set of task instances
 *DAGApi* | [**post_set_task_instances_state**](docs/DAGApi.md#post_set_task_instances_state) | **POST** /dags/{dag_id}/updateTaskInstancesState | Set a state of task instances
-*DAGRunApi* | [**clear_dag_run**](docs/DAGRunApi.md#clear_dag_run) | **POST** /dags/{dag_id}/dagRuns/{dag_run_id}/clear | Clear a DAG run
-*DAGRunApi* | [**delete_dag_run**](docs/DAGRunApi.md#delete_dag_run) | **DELETE** /dags/{dag_id}/dagRuns/{dag_run_id} | Delete a DAG run
-*DAGRunApi* | [**get_dag_run**](docs/DAGRunApi.md#get_dag_run) | **GET** /dags/{dag_id}/dagRuns/{dag_run_id} | Get a DAG run
-*DAGRunApi* | [**get_dag_runs**](docs/DAGRunApi.md#get_dag_runs) | **GET** /dags/{dag_id}/dagRuns | List DAG runs
-*DAGRunApi* | [**get_dag_runs_batch**](docs/DAGRunApi.md#get_dag_runs_batch) | **POST** /dags/~/dagRuns/list | List DAG runs (batch)
-*DAGRunApi* | [**get_upstream_dataset_events**](docs/DAGRunApi.md#get_upstream_dataset_events) | **GET** /dags/{dag_id}/dagRuns/{dag_run_id}/upstreamDatasetEvents | Get dataset events for a DAG run
-*DAGRunApi* | [**post_dag_run**](docs/DAGRunApi.md#post_dag_run) | **POST** /dags/{dag_id}/dagRuns | Trigger a new DAG run
-*DAGRunApi* | [**set_dag_run_note**](docs/DAGRunApi.md#set_dag_run_note) | **PATCH** /dags/{dag_id}/dagRuns/{dag_run_id}/setNote | Update the DagRun note.
-*DAGRunApi* | [**update_dag_run_state**](docs/DAGRunApi.md#update_dag_run_state) | **PATCH** /dags/{dag_id}/dagRuns/{dag_run_id} | Modify a DAG run
+*DAGRunApi* | [**clear_dag_run**](docs/DagRunApi.md#clear_dag_run) | **POST** /dags/{dag_id}/dagRuns/{dag_run_id}/clear | Clear a DAG run
+*DAGRunApi* | [**delete_dag_run**](docs/DagRunApi.md#delete_dag_run) | **DELETE** /dags/{dag_id}/dagRuns/{dag_run_id} | Delete a DAG run
+*DAGRunApi* | [**get_dag_run**](docs/DagRunApi.md#get_dag_run) | **GET** /dags/{dag_id}/dagRuns/{dag_run_id} | Get a DAG run
+*DAGRunApi* | [**get_dag_runs**](docs/DagRunApi.md#get_dag_runs) | **GET** /dags/{dag_id}/dagRuns | List DAG runs
+*DAGRunApi* | [**get_dag_runs_batch**](docs/DagRunApi.md#get_dag_runs_batch) | **POST** /dags/~/dagRuns/list | List DAG runs (batch)
+*DAGRunApi* | [**get_upstream_dataset_events**](docs/DagRunApi.md#get_upstream_dataset_events) | **GET** /dags/{dag_id}/dagRuns/{dag_run_id}/upstreamDatasetEvents | Get dataset events for a DAG run
+*DAGRunApi* | [**post_dag_run**](docs/DagRunApi.md#post_dag_run) | **POST** /dags/{dag_id}/dagRuns | Trigger a new DAG run
+*DAGRunApi* | [**set_dag_run_note**](docs/DagRunApi.md#set_dag_run_note) | **PATCH** /dags/{dag_id}/dagRuns/{dag_run_id}/setNote | Update the DagRun note.
+*DAGRunApi* | [**update_dag_run_state**](docs/DagRunApi.md#update_dag_run_state) | **PATCH** /dags/{dag_id}/dagRuns/{dag_run_id} | Modify a DAG run
 *DagWarningApi* | [**get_dag_warnings**](docs/DagWarningApi.md#get_dag_warnings) | **GET** /dagWarnings | List dag warnings
 *DatasetApi* | [**get_dataset**](docs/DatasetApi.md#get_dataset) | **GET** /datasets/{uri} | Get a dataset
 *DatasetApi* | [**get_dataset_events**](docs/DatasetApi.md#get_dataset_events) | **GET** /datasets/events | Get dataset events