portico: Break up long paragraphs on Why Zulip.

This breaks long paragraphs on the Why Zulip page into multiple
smaller paragraphs to improve readability.

templates/zerver/why-zulip.md

@@ -20,14 +20,18 @@ conversation in a busy channel at 10am, and Ada swings by sometime in
 the evening, there is no way for Ada to effectively participate in
 that conversation. If Ada is a manager who spends most of her days in
 meetings, or is a remote engineer living 8 time zones away, she won’t
-be able to participate in most conversations at all. This means that
+be able to participate in most conversations at all.
+
+This means that
 in an organization that has adopted Slack, the vast majority of Ada’s
 conversations will still be over email, during meetings, or over Slack
 direct messages.
 
 By contrast, Zulip’s lightweight threading model allows busy team
 members and remote workers to fully participate, even if they are
-reading messages hours after they are sent (or the next day!). This
+reading messages hours after they are sent (or the next day!).
+
+This
 enables conversation that would otherwise happen over meetings or
 email to happen in Zulip itself. It also enables easy participation
 and information spread to those that have the least time to attend
@@ -40,7 +44,9 @@ Email is clunky for real-time communication. A thread with even 50
 messages feels cluttered and slow, whereas real-time chat
 conversations (on any platform) regularly exceed that. Typing
 notifications, emoji reactions, keyboard shortcuts, and blazingly fast
-clients make Zulip a daily pleasure. Usability matters; in an
+clients make Zulip a daily pleasure.
+
+Usability matters; in an
 organization that relies on email for communication, things that could
 have been resolved over chat end up being pushed to meetings instead.
 
@@ -49,14 +55,16 @@ have been resolved over chat end up being pushed to meetings instead.
 The Zulip project has over 30 core team members, working from over 10
 different time zones and 25 different locations. Outside of one-on-one
 conversations, Zulip doesn’t have a single phone or video-based
-meeting. Zulip also has 0 internal mailing lists, and 0 internal email
+meeting. Zulip also has zero internal mailing lists, and zero internal email
 discussions. By contrast, even Slack doesn’t rely on Slack for remote
 work; their
 [careers page](https://slack.com/careers/location/all-locations/dept/all-departments)
 doesn’t list a single position where you could work from anywhere.
 
 Threaded conversations mean that all stakeholders can see and respond to
-every message, just like in meetings and email. But unlike meetings, Zulip
+every message, just like in meetings and email.
+
+But unlike meetings, Zulip
 conversations don’t require coordinating busy schedules, or hour long
 commitments from folks that just need a 5 minute update. And unlike email, a
 lively discussion of 300 Zulip messages is just as easy to digest and