Fix utf-8 guide link to otel page

Signed-off-by: Fiona Liao <[email protected]>

Author: fionaliao

content/docs/guides/utf8.md

@@ -97,7 +97,7 @@ OTLP receiver in Prometheus 3.0 still normalizes all names to Prometheus format
       translation_strategy: NoUTF8EscapingWithSuffixes
 
 
-See [OpenTelemetry guide](./opentelemetry) for more details.
+See [OpenTelemetry guide](opentelemetry.md) for more details.
 
 
 # Querying
@@ -119,4 +119,4 @@ Label names must also be quoted if they contain legacy-incompatible characters:
 `{"metric.name", "my.label.name"="bar"}`
 
 The metric name can appear anywhere inside the braces, but style prefers that it
-be the first term.
+be the first term.