docs(jira): document JIRA_SKIP_UNPARSEABLE_ISSUES in env.example

Requested in review on #9026.

Signed-off-by: Bhanu Chander Vallabaneni <v.bhanuchander@gmail.com>

Author: vbhanuchander-lang

env.example

@@ -87,6 +87,16 @@ USE_GO_GIT_IN_GIT_EXTRACTOR=false
 SKIP_COMMIT_STAT=false
 SKIP_COMMIT_FILES=true
 
+# In plugin jira, continue collecting when a page of issues cannot be parsed.
+# A page that returns a successful HTTP status but a body that is not the
+# expected JSON - a truncated payload, or an HTML error page substituted by a
+# proxy - normally fails the whole collectIssues subtask, discarding an
+# otherwise complete sync because of a single page. Set to true to log and skip
+# that page instead. Only parse failures on successful responses are affected;
+# HTTP error statuses keep their existing retry behaviour.
+##########################
+JIRA_SKIP_UNPARSEABLE_ISSUES=false
+
 # Set if response error when requesting /connections/{connection_id}/test should be wrapped or not
 ##########################
 WRAP_RESPONSE_ERROR=