[v0.18.0][Bugfix] Fix pr triggers on branches for nightly test workflows (#7695)

### What this PR does / why we need it?
1. Allow PR triggers on `*-dev` and `releases/v*` branches for nightly
test workflows.
2.  fix image-tag in doc

---------

Signed-off-by: hfadzxy <starmoon_zhang@163.com>

.github/workflows/dockerfiles/Dockerfile.nightly.a2

@@ -15,7 +15,7 @@
 # This file is a part of the vllm-ascend project.
 #
 
-FROM quay.io/ascend/vllm-ascend:release-0.18.0
+FROM quay.io/ascend/vllm-ascend:releases-v0.18.0
 
 ARG PIP_INDEX_URL="https://mirrors.tuna.tsinghua.edu.cn/pypi/web/simple"
 ARG AIS_BENCH_TAG="v3.0-20250930-master"

.github/workflows/schedule_nightly_test_a2.yaml

@@ -27,6 +27,8 @@ on:
   pull_request:
     branches:
       - 'main'
+      - '*-dev'
+      - 'releases/v*'
     types: [labeled, synchronize]
 
 permissions:

.github/workflows/schedule_nightly_test_a3.yaml

@@ -28,6 +28,8 @@ on:
   pull_request:
     branches:
       - 'main'
+      - '*-dev'
+      - 'releases/v*'
     types: [ labeled, synchronize ]
 
 permissions: