Add tip about installing docbook-xml and docbook-xsl on Debian

diff --git a/doc/INSTALL.md b/doc/INSTALL.md
index b20dd424333fc3b071b30597986b7cca4ee12ea8..77c2a72342090b4df70986e83a82f824b8913b27 100644 (file)
--- a/doc/INSTALL.md
+++ b/doc/INSTALL.md
@@ -25,6 +25,9 @@ Optional:
 - GNU Bourne Again SHell (bash) for tests.
 - [AsciiDoc](https://www.methods.co.nz/asciidoc/) to build the HTML
   documentation.
+  - Tip: On Debian-based systems (e.g. Ubuntu), install the `docbook-xml` and
+    `docbook-xsl` packages in addition to `asciidoc`. Without the former the
+    man page generation will be very slow.
 - [xsltproc](http://xmlsoft.org/XSLT/xsltproc2.html) to build the man page.
 - [Python](https://www.python.org) to debug and run the performance test suite.