[csrng/doc] Application Interface and Genbits update

This PR dramaitically expands the technical  specification for the CSRNG IP.  It
includes:

-Decription of the application interface
-Structure of the per-instance working state
-Command Structure, and
-Block Diagrams.

Co-Authored by @mwbranstad and @martin-lueker

Signed-off-by: Martin Lueker-Boden <martin.lueker-boden@wdc.com>
diff --git a/util/build_docs.py b/util/build_docs.py
index 8b0c647..ebf0dbe 100755
--- a/util/build_docs.py
+++ b/util/build_docs.py
@@ -51,6 +51,7 @@
         "hw/ip/aes/data/aes.hjson",
         "hw/top_earlgrey/ip/alert_handler/data/autogen/alert_handler.hjson",
         "hw/ip/entropy_src/data/entropy_src.hjson",
+        "hw/ip/csrng/data/csrng.hjson",
         "hw/ip/flash_ctrl/data/flash_ctrl.hjson",
         "hw/ip/gpio/data/gpio.hjson",
         "hw/ip/hmac/data/hmac.hjson",