Revert "Remove HTML builds of librmm (#1415)" (#1604)

This reverts commit 77b5500.

See: rapidsai/docs#517 (review)

We need to have librmm docs published in order to enable cross-linking of librmm from libcudf docs.

From discussion with @raydouglass, we don't need to link to them publicly on docs.rapids.ai, as they are already included in the rmm docs (both C++ and Python). The librmm docs will just be used to cross-reference from libcudf docs.

Authors:
  - Bradley Dice (https://github.com/bdice)

Approvers:
  - Ray Douglass (https://github.com/raydouglass)
  - Vyas Ramasubramani (https://github.com/vyasr)

URL: #1604

Author: bdice

ci/build_docs.sh

@@ -33,6 +33,8 @@ export RAPIDS_DOCS_DIR="$(mktemp -d)"
 rapids-logger "Build CPP docs"
 pushd doxygen
 doxygen Doxyfile
+mkdir -p "${RAPIDS_DOCS_DIR}/librmm/html"
+mv html/* "${RAPIDS_DOCS_DIR}/librmm/html"
 popd
 
 rapids-logger "Build Python docs"

doxygen/Doxyfile

@@ -1135,7 +1135,7 @@ IGNORE_PREFIX          =
 # If the GENERATE_HTML tag is set to YES, doxygen will generate HTML output
 # The default value is: YES.
 
-GENERATE_HTML          = NO
+GENERATE_HTML          = YES
 
 # The HTML_OUTPUT tag is used to specify where the HTML docs will be put. If a
 # relative path is entered the value of OUTPUT_DIRECTORY will be put in front of