PDFBOX-4605: fix link to Apache PDFBox git repo; add clone command
diff --git a/content/building.md b/content/building.md
index 00ab8cc..45dfcac 100644
--- a/content/building.md
+++ b/content/building.md
@@ -35,7 +35,10 @@
We also have a read-only [Git mirror](https://git.apache.org/) which is further mirrored to GitHub as [apache/pdfbox](https://github.com/apache/pdfbox).
-The sources for the **Java ImageIO plugin for the JBIG2 image format** are available in the [Apache Git Repository](https://git-wip-us.apache.org/repos/asf?p=pdfbox-jbig2.git) or can be loaded from [GitHub](https://github.com/apache/pdfbox-jbig2).
+The sources for the **Java ImageIO plugin for the JBIG2 image format** are available in the [Apache Git Repository](https://git-wip-us.apache.org/repos/asf/pdfbox-jbig2.git) or can be loaded from [GitHub](https://github.com/apache/pdfbox-jbig2):
+
+ git clone https://git-wip-us.apache.org/repos/asf/pdfbox-jbig2.git
+ cd pdfbox-jbig2
## Build dependencies
