correct number of options in global config block (#960)

content/docs/introduction/first_steps.md

@@ -53,7 +53,7 @@ scrape_configs:
 
 There are three blocks of configuration in the example configuration file: `global`, `rule_files`, and `scrape_configs`. 
 
-The `global` block controls the Prometheus server's global configuration. We have three options present. The first, `scrape_interval`, controls how often Prometheus will scrape targets. You can override this for individual targets. In this case the global setting is to scrape every 15 seconds. The `evaluation_interval` option controls how often Prometheus will evaluate rules. Prometheus uses rules to create new time series and to generate alerts.
+The `global` block controls the Prometheus server's global configuration. We have two options present. The first, `scrape_interval`, controls how often Prometheus will scrape targets. You can override this for individual targets. In this case the global setting is to scrape every 15 seconds. The `evaluation_interval` option controls how often Prometheus will evaluate rules. Prometheus uses rules to create new time series and to generate alerts.
 
 The `rule_files` block specifies the location of any rules we want the Prometheus server to load. For now we've got no rules.
 
@@ -168,4 +168,4 @@ One useful metric to look for is the `up` metric. The `up` metric can be used to
 
 ## Summary
 
-Now you've been introduced to Prometheus, installed it, and configured it to monitor your first resources. We've also installed our first exporter and seen the basics of how to work with time series data scraped using the expression browser. You can find more [documentation](/docs/introduction/overview/) and [guides](/docs/guides/) to help you continue to learn more about Prometheus. 
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+Now you've been introduced to Prometheus, installed it, and configured it to monitor your first resources. We've also installed our first exporter and seen the basics of how to work with time series data scraped using the expression browser. You can find more [documentation](/docs/introduction/overview/) and [guides](/docs/guides/) to help you continue to learn more about Prometheus.