Update zk_login.md (MystenLabs#13677)

## Description 

Describe the changes or additions included in this PR.

## Test Plan 

How did you test the new or updated feature?

---
If your changes are not user-facing and not a breaking change, you can
skip the following section. Otherwise, please indicate what changed, and
then add to the Release Notes section as highlighted during the release
process.

### Type of Change (Check all that apply)

- [ ] protocol change
- [ ] user-visible impact
- [ ] breaking change for a client SDKs
- [ ] breaking change for FNs (FN binary must upgrade)
- [ ] breaking change for validators or node operators (must upgrade
binaries)
- [ ] breaking change for on-chain data layout
- [ ] necessitate either a data wipe or data migration

### Release notes

doc/src/build/zk_login.md

@@ -70,17 +70,14 @@ In Mainnet, you must configure the client ID (`$CLIENT_ID`) and redirect URL (`$
 1. Select "APIs & Services" then "Credentials", where you can find the client ID. Set the redirect URL. This should be the wallet or application front end.
 
 ![1](../../static/zklogin-google1.png "Sign up for Google developer account")
-
 *Sign up for Google developer account*
 <p>&nbsp;</p>
 
 ![2](../../static/zklogin-google2.png "Go to Credentials")
-
 *Go to Credentials*
 <p>&nbsp;</p>
 
 ![3](../../static/zklogin-google3.png "Configure Redirect URL")
-
 *Configure a Redirect URL*
 
 ### Facebook
@@ -90,12 +87,10 @@ In Mainnet, you must configure the client ID (`$CLIENT_ID`) and redirect URL (`$
 1. Select "Build your app" then "Products" then "Facebook Login" where you can find the client ID. Set the redirect URL. This should be the wallet or application frontend.
 
 ![1](../../static/zklogin-facebook1.png "Sign up for Facebook developer account")
-
 *Sign up for Facebook developer account*
 <p>&nbsp;</p>
 
 ![2](../../static/zklogin-facebook2.png "Go to Settings")
-
 *Go to Settings*
 
 ### Twitch
@@ -105,12 +100,10 @@ In Mainnet, you must configure the client ID (`$CLIENT_ID`) and redirect URL (`$
 1. Go to "Register Your Application" then "Application" where you can find the client ID. Set the redirect URL. This should be the wallet or application frontend.
 
 ![1](../../static/zklogin-twitch1.png "Sign up for Twitch developer account")
-
 *Sign up for Twitch developer account*
 <p>&nbsp;</p>
 
 ![2](../../static/zklogin-twitch2.png "Go to Console")
-
 *Go to Console*
 
 ## Set Up OAuth Flow