Some grammar an typo fixes.

sig-scalability/extending_slo.md

@@ -25,10 +25,12 @@ This includes current SLOs:
 - API call latency
 - E2e Pod startup latency
 
-By churn we understand a measure of amount changes happening in the cluster. It's formal(-ish) definition will follow, but informally it can be thought about as number of user-issued requests per second plus number of pods affected by those requests. 
+By churn we understand a measure of amount changes happening in the cluster. Its formal(-ish) definition will follow, but informally it can be thought about as number of user-issued requests per second plus number of pods affected by those requests.
 
 More formally churn per second is defined as:
+```
 #Pod creations + #PodSpec updates + #user originated requests in a given second
+```
 The last part is necessary only to get rid of situations when user is spamming API server with various requests. In ordinary circumstances we expect it to be in the order of 1-2. 
 
 ## Burst SLOs
@@ -38,8 +40,8 @@ This includes the new SLO:
 - Pod startup throughput
 
 ## Environment
-Kubernetes cluster in which we benchmark SLOs need to meet following criteria:
-- Run a single master machine appropriately sized
+A Kubernetes cluster in which we benchmark SLOs needs to meet the following criteria:
+- Run a single appropriately sized master machine
 - Main etcd runs as a single instance on the master machine
 - Events are stored in a separate etcd instance running on the master machine
 - Kubernetes version is at least 1.X.Y
@@ -59,7 +61,7 @@ All our performance SLOs should be defined using the following template:
 _One-two sentences describing the SLO, that's possible to understand by the majority of the community_
 
 ### User Stories
-_Few user stories showing in what situations users might be interested in this SLO, and why other ones are not enough_
+_A Few user stories showing in what situations users might be interested in this SLO, and why other ones are not enough_
 
 ## Full definition
 ### Test description