Prefix rfcbot concerns with "concerns:" text

Author: Urgau

templates/_issues_rfcbot.tt

@@ -5,7 +5,7 @@
 {%- if issue.fcp_details is object %}
 {{indent}}- {{issue.fcp_details.disposition}}: [{{issue.title}} ({{issue.repo_name}}#{{issue.number}})]({{issue.fcp_details.bot_tracking_comment_html_url}})
 {{indent}}{{indent}}-{% for reviewer in issue.fcp_details.pending_reviewers %} @{% if issue.fcp_details.should_mention %}{% else %}_{% endif %}**|{{reviewer.zulip_id}}**{%else%} no pending checkboxs{% endfor %}
-{{indent}}{{indent}}-{% for concern in issue.fcp_details.concerns %} [{{concern.name}} (by {{concern.reviewer_login}})]({{concern.concern_url}}){%else%} no pending concerns{% endfor -%}
+{{indent}}{{indent}}-{% if issue.fcp_details.concerns|length > 0 %} concerns:{% endif %}{% for concern in issue.fcp_details.concerns %} [{{concern.name}} (by {{concern.reviewer_login}})]({{concern.concern_url}}){%else%} no pending concerns{% endfor -%}
 {% else %}
 {{indent}}- {{issue::render(issue=issue)}}
 {%- endif -%}