Corrects a single typo (#1131)

I make this error in my own writing constantly.

pages/sending/files.rst

@@ -9,7 +9,7 @@ The collectors can be configured and controlled by the already available configu
 
 Of course, you can still use any program supporting the GELF or Syslog protocol (among others) to send your logs to Graylog.
 
-The most recommended way to pick a log file from Windows or Linux systems is `filebeat <https://www.elastic.co/guide/en/beats/filebeat/current/filebeat-overview.html>`__. This collector is build to collect log files and ship them to a central location. The output module in filebeat is called logstash needed to send messages to a Graylog beats input. 
+The most recommended way to pick a log file from Windows or Linux systems is `filebeat <https://www.elastic.co/guide/en/beats/filebeat/current/filebeat-overview.html>`__. This collector is built to collect log files and ship them to a central location. The output module in filebeat is called logstash needed to send messages to a Graylog beats input. 
 
 
 A basic filebeat configuration for filebeat on Linux can look like the following::