Update weekly_build.yaml

Add workflow_dispatch so it is possible to run the build manually

Signed-off-by: Rafael Sene <rafael@riscv.org>

.github/workflows/weekly_build.yaml

@@ -4,6 +4,7 @@ on:
   schedule:
     # This will run every week at 00:00 UTC on Monday
     - cron: '0 0 * * 1'
+  workflow_dispatch:
 
 jobs:
   build-and-push-docker-image:
@@ -51,4 +52,4 @@ jobs:
           tag_name: release-${{ steps.current_date.outputs.date }}-${{ github.sha }}
           release_name: Release ${{ steps.current_date.outputs.date }}-${{ github.sha }}
           body: |
-            This release contains the latest container image built by this repository and hosted at [riscvintl/riscv-docs-base-container-image:latest](https://hub.docker.com/r/riscvintl/riscv-docs-base-container-image/tags?page=1&ordering=last_updated&name=latest).
+            This release contains the latest container image built by this repository and hosted at [riscvintl/riscv-docs-base-container-image:latest](https://hub.docker.com/r/riscvintl/riscv-docs-base-container-image/tags?page=1&ordering=last_updated&name=latest).