docs: add headings

Author: alespour

README.md

@@ -63,6 +63,8 @@ dependencies {
 
 ## Usage
 
+### Create client
+
 To start with the client, import the `com.influxdb.v3.client` package and create a `InfluxDBClient` by:
 
 ```java
@@ -91,7 +93,9 @@ public class IOxExample {
 }
 ```
 
-to insert data, you can use code like this:
+### Write
+
+To insert data, you can use code like this:
 
 ```java
 //
@@ -144,7 +148,7 @@ String record = "temperature,location=north value=60.0";
 client.writeRecord(record);
 ```
 
-### Accept partial writes and inspect failed lines
+#### Accept partial writes and inspect failed lines
 
 Partial writes are enabled by default.
 `acceptPartial` can be configured in three ways: client defaults via `WriteOptions`, connection string / environment variable / system property (`writeAcceptPartial` / `INFLUX_WRITE_ACCEPT_PARTIAL` / `influx.writeAcceptPartial`), or per-write `WriteOptions`.
@@ -158,15 +162,17 @@ With InfluxDB Core/Enterprise, when a write request fails due to one or more inv
 When partial writes are disabled, any rejected line causes all lines to be rejected.
 InfluxDB Clustered does not return this structured partial-write error format.
 
-### Compatibility with InfluxDB Clustered
+#### Compatibility with InfluxDB Clustered
 
 For InfluxDB Clustered, enable `useV2Api` for writes.
 Like other write options, this can be configured in client code, connection string / environment variable / system property (`writeUseV2Api` / `INFLUX_WRITE_USE_V2_API` / `influx.writeUseV2Api`), or per-write `WriteOptions`.
 
 If `useV2Api` is set, `acceptPartial` is ignored because this compatibility mode does not support partial-write controls.
 Any rejected line causes all lines to be rejected.
 
-to query your data, you can use code like this:
+### Query
+
+To query your data, you can use code like this:
 
 ```java
 //