Document `refdoc' usage.
* docs/reference/README: Add information and instructions to use targets
`make refdoc' and the new `make refdoc-venv'. Also add troubleshooting
tips.
diff --git a/docs/reference/README b/docs/reference/README
index 51b04d6..3ffcfc0 100644
--- a/docs/reference/README
+++ b/docs/reference/README
@@ -1,5 +1,35 @@
-After saying `make refdoc' this directory contains the FreeType API
-reference. You need python to make this target.
+After saying `make refdoc' or `make refdoc-venv' the `site/' directory
+contains the FreeType API reference. You need python and pip to make this
+target.
+
+There are two ways to generate the documentation:
+
+1. Using `make refdoc':
+
+ - Ensure `python' and `pip' are available.
+ - Install pip package `docwriter' with `pip install --user docwriter'.
+ - Make target with `make refdoc'.
+ - This target can be run offline once required packages are installed.
+
+2. Using `make refdoc-venv' (requires internet access):
+
+ - Ensure `python', `pip' and python package `virtualenv' are available.
+ - Make target with `make refdoc-venv'.
+ - This may or may not require internet access every time depending on
+ pip and system caching.
This also works with Jam: Just type `jam refdoc' in the main directory.
+Some troubleshooting tips:
+
+* Regularly run `pip install --upgrade docwriter' to check for updates which
+may include bug fixes.
+
+* Ensure that `docwriter' is installed in the same python target that
+`make refdoc' uses (python3/python2/python).
+
+* `pip' and `python' may point to different versions of Python. Check using
+`python --version' and `pip --version'.
+
+* If none of this works, send a mail to `freetype-devel@nongnu.org' or file
+an issue at `https://github.com/freetype/docwriter/issues'.
