docs: add examples and improve documentation brevity

- Add basic usage example
- Add custom histogram bounds example
- Add OTLP exporter example
- Significantly reduce documentation verbosity
- Delegate unit conversion details to Unit documentation
- Clarify that descriptions/bounds only apply to metrics created after they are set

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: palindrom615

Cargo.toml

@@ -51,8 +51,6 @@ noisy_float = { version = "0.2", default-features = false }
 once_cell = { version = "1", default-features = false, features = ["std"] }
 opentelemetry = { version = "0.30", default-features = false }
 opentelemetry_sdk = { version = "0.30", default-features = false }
-opentelemetry-otlp = { version = "0.30", default-features = false }
-opentelemetry-stdout = { version = "0.30", default-features = false }
 ordered-float = { version = "4.2", default-features = false }
 parking_lot = { version = "0.12", default-features = false }
 portable-atomic = { version = "1", default-features = false }

metrics-exporter-opentelemetry/examples/basic.rs

@@ -0,0 +1,32 @@
+use std::thread;
+use std::time::Duration;
+use opentelemetry::metrics::MeterProvider;
+use metrics::{counter, describe_counter, describe_histogram, gauge, histogram, Unit};
+use metrics_exporter_opentelemetry::OpenTelemetryRecorder;
+use opentelemetry_sdk::metrics::SdkMeterProvider;
+
+fn main() {
+    // Create OpenTelemetry provider and meter
+    let provider = SdkMeterProvider::default();
+    let meter = provider.meter("example_app");
+    
+    // Create and install the OpenTelemetry recorder
+    let recorder = OpenTelemetryRecorder::new(meter);
+    metrics::set_global_recorder(recorder).expect("failed to install recorder");
+
+    // Register metrics with descriptions and units
+    describe_counter!("requests_total", Unit::Count, "Total HTTP requests");
+    describe_histogram!("response_time", Unit::Seconds, "Response time distribution");
+
+    // Loop and record metrics
+    for i in 0..10 {
+        counter!("requests_total", "method" => "GET", "status" => "200").increment(1);
+        gauge!("cpu_usage").set(45.0 + (i as f64 * 2.0));
+        histogram!("response_time").record(0.1 + (i as f64 * 0.01));
+        
+        println!("Recorded metrics iteration {}", i + 1);
+        thread::sleep(Duration::from_millis(500));
+    }
+    
+    println!("Example completed");
+}

metrics-exporter-opentelemetry/examples/custom_histogram_bounds.rs

@@ -0,0 +1,50 @@
+use std::thread;
+use std::time::Duration;
+use opentelemetry::metrics::MeterProvider;
+use metrics::{describe_histogram, histogram, KeyName, Unit};
+use metrics_exporter_opentelemetry::OpenTelemetryRecorder;
+use opentelemetry_sdk::metrics::SdkMeterProvider;
+
+fn main() {
+    // Create OpenTelemetry provider and meter
+    let provider = SdkMeterProvider::default();
+    let meter = provider.meter("histogram_example");
+    
+    // Create the recorder
+    let recorder = OpenTelemetryRecorder::new(meter);
+    
+    // Set custom histogram boundaries BEFORE installing the recorder
+    recorder.set_histogram_bounds(
+        &KeyName::from("latency"),
+        vec![0.001, 0.005, 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1.0, 2.5, 5.0, 10.0]
+    );
+    
+    recorder.set_histogram_bounds(
+        &KeyName::from("request_size"),
+        vec![1024.0, 4096.0, 16384.0, 65536.0, 262144.0, 1048576.0]
+    );
+    
+    // Install the recorder
+    metrics::set_global_recorder(recorder).expect("failed to install recorder");
+
+    // Describe the histograms
+    describe_histogram!("latency", Unit::Seconds, "Request latency");
+    describe_histogram!("request_size", Unit::Bytes, "Request size");
+
+    // Record various values to see the custom buckets in action
+    let latency_values = [0.002, 0.008, 0.015, 0.035, 0.075, 0.15, 0.3, 0.7, 1.5, 3.0, 7.0];
+    let size_values = [512.0, 2048.0, 8192.0, 32768.0, 131072.0, 524288.0, 2097152.0];
+    
+    for (i, &latency) in latency_values.iter().enumerate() {
+        histogram!("latency", "endpoint" => "/api/users").record(latency);
+        
+        if i < size_values.len() {
+            histogram!("request_size", "endpoint" => "/api/users").record(size_values[i]);
+        }
+        
+        println!("Recorded latency: {}s, size: {}B", latency, size_values.get(i).unwrap_or(&0.0));
+        thread::sleep(Duration::from_millis(300));
+    }
+    
+    println!("Custom histogram bounds example completed");
+}