docs: add more known issues

A clean must be performed when the theme is switched and
incremental building does not work if printouts are enabled. Add
this information to the README.

Signed-off-by: John Ogness <john.ogness@linutronix.de>

1 files changed, 5 insertions, 0 deletions

diff --git a/README b/README
index bbc22c8..6809ffb 100644
--- a/README
+++ b/README
@@ -58,3 +58,8 @@ Known Issues
 ~~~~~~~~~~~~
 
   * Building in parallel using `-j` is not supported.
+
+  * A `make clean` must be performed if the theme is changed.
+
+  * If printouts are enabled, incremental building does not work,
+    i.e. a full rebuild occurs every time on `make`.