Add requirements for docs generation

Makefile

@@ -3,6 +3,7 @@
 compile-requirements: ## Compile requirements files
 	pip-compile -o requirements/base.txt requirements/base.in
 	pip-compile -o requirements/dev.txt requirements/dev.in
+	pip-compile -o requirements/docs.txt requirements/docs.in
 
 bundle: ## Bundle the tutor package in a single "dist/tutor" executable
 	pyinstaller --onefile --name=tutor --add-data=./tutor/templates:./tutor/templates ./bin/main

requirements/docs.in

@@ -0,0 +1,2 @@
+sphinx
+sphinx-rtd-theme

requirements/docs.txt

@@ -0,0 +1,26 @@
+#
+# This file is autogenerated by pip-compile
+# To update, run:
+#
+#    pip-compile --output-file requirements/docs.txt requirements/docs.in
+#
+alabaster==0.7.12         # via sphinx
+babel==2.6.0              # via sphinx
+certifi==2018.11.29       # via requests
+chardet==3.0.4            # via requests
+docutils==0.14            # via sphinx
+idna==2.8                 # via requests
+imagesize==1.1.0          # via sphinx
+jinja2==2.10              # via sphinx
+markupsafe==1.1.0         # via jinja2
+packaging==19.0           # via sphinx
+pygments==2.3.1           # via sphinx
+pyparsing==2.3.1          # via packaging
+pytz==2018.9              # via babel
+requests==2.21.0          # via sphinx
+six==1.12.0               # via packaging, sphinx
+snowballstemmer==1.2.1    # via sphinx
+sphinx-rtd-theme==0.4.3
+sphinx==1.8.4
+sphinxcontrib-websupport==1.1.0  # via sphinx
+urllib3==1.24.1           # via requests