Add note about pre installed libs
@@ -102,7 +102,12 @@ The build process is executed inside Docker containers,
by default the image used is ``readthedocs/build:2.0``,
but you can change that using a :doc:`configuration file <yaml-config>`.
-Each image is described below.
+.. note::
+
+ The build server does have a select number of C libraries installed,
+ because they are used across a wide array of python projects.
+ We can't install every C library out there,
+ but we try and support the major ones
2.0 (stable)
~~~~~~~~~~~~
