update wiki pages

CHANGELOG.md

@@ -20,6 +20,7 @@ If you use alerting rules or Grafana dashboards, which rely on this metric, then
 
 * FEATURE: add `-search.setLookbackToStep` command-line flag, which enables InfluxDB-like gap filling during querying. See [these docs](https://docs.victoriametrics.com/guides/migrate-from-influx.html) for details.
 * FEATURE: [vmui](https://docs.victoriametrics.com/#vmui): add an UI for [query tracing](https://docs.victoriametrics.com/#query-tracing). It can be enabled by clicking `enable query tracing` checkbox and re-running the query. See [this feature request](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/2703).
+* FEATURE: [vmagent](https://docs.victoriametrics.com/vmagent.html): add `-remoteWrite.headers` command-line option for specifying optional HTTP headers to send to the configured `-remoteWrite.url`. For example, `-remoteWrite.headers='Foo:Bar^^Baz:x'` would send `Foo: Bar` and `Baz: x` HTTP headers with every request to `-remoteWrite.url`. See [this feature request](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/2805).
 * FEATURE: [vmagent](https://docs.victoriametrics.com/vmagent.html): add ability to specify additional HTTP headers to send to scrape targets via `headers` section in `scrape_configs`. This can be used when the scrape target requires custom authorization and authentication like in [this stackoverflow question](https://stackoverflow.com/questions/66032498/prometheus-scrape-metric-with-custom-header). For example, the following config instructs sending `My-Auth: top-secret` and `TenantID: FooBar` headers with each request to `http://host123:8080/metrics`:
 
 ```yaml

vmagent.md

@@ -1016,6 +1016,9 @@ See the docs at https://docs.victoriametrics.com/vmagent.html .
      Supports an array of values separated by comma or specified via multiple flags.
   -remoteWrite.flushInterval duration
      Interval for flushing the data to remote storage. This option takes effect only when less than 10K data points per second are pushed to -remoteWrite.url (default 1s)
+  -remoteWrite.headers array
+     Optional HTTP headers to send with each request to -remoteWrite.url. For example, -remoteWrite.headers='My-Auth:foobar' would send 'My-Auth: foobar' HTTP header with every request to -remoteWrite.url. Multiple headers must be delimited by '^^': -remoteWrite.headers='header1:value1^^header2:value2'
+     Supports an array of values separated by comma or specified via multiple flags.
   -remoteWrite.label array
      Optional label in the form 'name=value' to add to all the metrics before sending them to -remoteWrite.url. Pass multiple -remoteWrite.label flags in order to add multiple labels to metrics before sending them to remote storage
      Supports an array of values separated by comma or specified via multiple flags.