docs/Single-server-VictoriaMetrics.md: mention that VictoriaMetrics sanitizes metric names in DataDog data by default

This is a follow-up for 7c2474dac7

README.md

@@ -432,6 +432,10 @@ This command should return the following output if everything is OK:
 {"metric":{"__name__":"system.load.1","environment":"test","host":"test.example.com"},"values":[0.5],"timestamps":[1632833641000]}
 ```
 
+VictoriaMetrics automatically sanitizes metric names for the data ingested via DataDog protocol
+according to [DataDog metric naming recommendations](https://docs.datadoghq.com/metrics/custom_metrics/#naming-custom-metrics).
+If you need accepting metric names as is without sanitizing, then pass `-datadog.sanitizeMetricName=false` command-line flag to VictoriaMetrics.
+
 Extra labels may be added to all the written time series by passing `extra_label=name=value` query args.
 For example, `/datadog/api/v1/series?extra_label=foo=bar` would add `{foo="bar"}` label to all the ingested metrics.
 

docs/README.md

@@ -432,6 +432,10 @@ This command should return the following output if everything is OK:
 {"metric":{"__name__":"system.load.1","environment":"test","host":"test.example.com"},"values":[0.5],"timestamps":[1632833641000]}
 ```
 
+VictoriaMetrics automatically sanitizes metric names for the data ingested via DataDog protocol
+according to [DataDog metric naming recommendations](https://docs.datadoghq.com/metrics/custom_metrics/#naming-custom-metrics).
+If you need accepting metric names as is without sanitizing, then pass `-datadog.sanitizeMetricName=false` command-line flag to VictoriaMetrics.
+
 Extra labels may be added to all the written time series by passing `extra_label=name=value` query args.
 For example, `/datadog/api/v1/series?extra_label=foo=bar` would add `{foo="bar"}` label to all the ingested metrics.
 

docs/Single-server-VictoriaMetrics.md

@@ -436,6 +436,10 @@ This command should return the following output if everything is OK:
 {"metric":{"__name__":"system.load.1","environment":"test","host":"test.example.com"},"values":[0.5],"timestamps":[1632833641000]}
 ```
 
+VictoriaMetrics automatically sanitizes metric names for the data ingested via DataDog protocol
+according to [DataDog metric naming recommendations](https://docs.datadoghq.com/metrics/custom_metrics/#naming-custom-metrics).
+If you need accepting metric names as is without sanitizing, then pass `-datadog.sanitizeMetricName=false` command-line flag to VictoriaMetrics.
+
 Extra labels may be added to all the written time series by passing `extra_label=name=value` query args.
 For example, `/datadog/api/v1/series?extra_label=foo=bar` would add `{foo="bar"}` label to all the ingested metrics.