ifctester - move build-ids-docs target to ifctester Makefile

Also added a note why it lives in test folder and added it's output to gitignore.

src/ifctester/Makefile

@@ -96,3 +96,8 @@ webapp-prepare: webapp-build
 .PHONY: test
 test:
 	pytest -p no:pytest-blender test
+
+.PHONY: build-ids-docs
+build-ids-docs:
+	mkdir -p test/build
+	cd test && python ids_doc_generator.py

src/ifctester/test/ids_doc_generator.py

@@ -16,6 +16,16 @@
 # You should have received a copy of the GNU Lesser General Public License
 # along with IfcTester.  If not, see <http://www.gnu.org/licenses/>.
 
+"""
+Documentation generator for IfcTester IDS facets and test cases.
+
+This is not a test file. It lives in the test/ directory because it reuses
+test cases from test_facet.py and test_ids.py to generate example IFC files,
+IDS files, and Markdown documentation into test/build/.
+
+Run via: make build-ids-docs (from src/ifctester/)
+"""
+
 import functools
 import os
 import re