Update getting-started.md with Bandit (#4518)

Co-authored-by: Severin Neumann <[email protected]>
Co-authored-by: opentelemetrybot <[email protected]>
Co-authored-by: Phillip Carter <[email protected]>

Author: 4 people

content/en/docs/languages/erlang/getting-started.md

@@ -47,9 +47,14 @@ We'll need a few other dependencies that Phoenix doesn't come with.
   OpenTelemetry Collector and/or to self-hosted or commercial services.
 - `opentelemetry_phoenix`: creates OpenTelemetry spans from the Elixir
   `:telemetry` events created by Phoenix.
-- `opentelemetry_cowboy`: creates OpenTelemetry spans from the Elixir
-  `:telemetry` events created by the Cowboy web server (which is used by
-  Phoenix).
+- web server dependencies: There are currently two options for web servers and
+  each has their telemetry counterpart. Phoenix applications post 1.7.11 default
+  to Bandit while pre 1.7.11 default to Cowboy. Both choices are valid. Use one
+  of the below options based on the web server your Phoenix application uses:
+  - `opentelemetry_cowboy`: creates OpenTelemetry spans from the Elixir
+    `:telemetry` events created by the Cowboy web server
+  - `opentelemetry_bandit`: creates OpenTelemetry spans from the Elixir
+    `:telemetry` events created by the Bandit web server
 
 ```elixir
 # mix.exs
@@ -59,7 +64,10 @@ def deps do
     {:opentelemetry_api, "~> {{% param versions.otelApi %}}"},
     {:opentelemetry_exporter, "~> {{% param versions.otelExporter %}}"},
     {:opentelemetry_phoenix, "~> {{% param versions.otelPhoenix %}}"},
-    {:opentelemetry_cowboy, "~> {{% param versions.otelCowboy %}}"},
+    # for Cowboy
+    {:opentelemetry_cowboy, "~> {{% param versions.otelCowboy %}}"}
+    # for Bandit
+    {:opentelemetry_bandit, "~> {{% version-from-registry instrumentation-erlang-bandit %}}"},
   ]
 end
 ```
@@ -70,8 +78,12 @@ The last two also need to be setup when your application starts:
 # application.ex
 @impl true
 def start(_type, _args) do
+  # Depending on what webserver you are using, you will either use:
   :opentelemetry_cowboy.setup()
   OpentelemetryPhoenix.setup(adapter: :cowboy2)
+  # or
+  OpentelemetryBandit.setup()
+  OpentelemetryPhoenix.setup(adapter: :bandit)
 end
 ```