removed style cruft in the NIM known issues doc (#1017)

Author: travisamartin

content/nim/releases/known-issues.md

@@ -441,24 +441,13 @@ The list of Threat Campaigns will disappear when scrolling down, preventing the
 #### Workaround
 
 Threat Campaign versions can be published with the API using the route: `api/platform/v1/security/publish`
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 ## 2.6.0
 
 November 17, 2022
 
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 ### {{% icon-bug %}} External references are not supported in App Protect policies {#36265}
 
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@@ -479,11 +468,6 @@ For example, in the NGINX App Protect WAF JSON declarative policy, these referen
 
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-## 2.5.0
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-October 04, 2022
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 ## 2.3.0
 
 June 30, 2022
@@ -514,28 +498,10 @@ filterBy=<dimension-name>!= ''
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-## 2.2.0
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-May 25, 2022
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-## 2.1.0
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-April 05, 2022
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 ## 2.0.0
 
 December 21, 2021
 
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 ### {{% icon-bug %}} Web interface doesn’t report error when failing to upload large config files {#31081}
 
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