docs: add examples to README.md

README.md

@@ -7,6 +7,59 @@ Package pgx-geos provides [PostGIS](https://postgis.net/) and
 [`github.com/jackc/pgx/v5`](https://pkg.go.dev/github.com/jackc/pgx/v5) via
 [`*github.com/twpayne/go-geos.Geom`](https://pkg.go.dev/github.com/twpayne/go-geos#Geom).
 
+## Usage
+
+### Single connection
+
+```go
+import (
+    // ...
+
+    "github.com/jackc/pgx/v5"
+    "github.com/twpayne/go-geos"
+    pgxgeos "github.com/twpayne/pgx-geos"
+)
+
+// ...
+
+    connectionStr := os.Getenv("DATABASE_URL")
+    conn, err := pgx.Connect(context.Background(), connectionStr)
+    if err != nil {
+        return err
+    }
+    if err := pgxgeos.Register(ctx, conn, geos.NewContext()); err != nil {
+        return err
+    }
+```
+
+### Connection pool
+
+```go
+import (
+    // ...
+
+    "github.com/jackc/pgx/v5/pgxpool"
+)
+
+// ...
+
+    config, err := pgxpool.ParseConfig(connectionStr)
+    if err != nil {
+        return err
+    }
+    config.AfterConnect = func(ctx context.Context, conn *pgx.Conn) error {
+        if err := pgxgeos.Register(ctx, conn, geos.NewContext()); err != nil {
+            return err
+        }
+        return nil
+    }
+
+    pool, err := pgxpool.NewWithConfig(context.Background(), config)
+    if err != nil {
+        return err
+    }
+```
+
 ## License
 
 MIT