Fix(docs): fix character escape in .mdx file (#750)

.mdx files crash when `{` characters are not escaped. 

Also fix capitalization and remove "patch 0" as this goes against our
convention.

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Author: jdpleiness

docs/technical-changelog.mdx

@@ -4,7 +4,7 @@ This page documents all notable changes to Sourcegraph. For more detailed change
 
 {/* CHANGELOG_START */}
 
-# sourcegraph 5 Release 9 Patch 0
+# Sourcegraph 5 Release 9
 
 ## v5.9.0
 
@@ -126,7 +126,7 @@ that we observed on the user's incoming request
 
 #### Site Admin
 
-- site config 'telemetry: { disableLocalEventLogs }' to disable event_logs [#1275](https://github.com/sourcegraph/sourcegraph/pull/1275)
+- site config 'telemetry: \{ disableLocalEventLogs \}' to disable event_logs [#1275](https://github.com/sourcegraph/sourcegraph/pull/1275)
   - Long-term local retention of user telemetry as 'event logs' can now be disabled entirely via the `telemetry: { disableLocalEventLogs }` site configuration.
 
 #### Sub_repo_perms