add mdx-linkify to markdown extensions

requirements/requirements.txt

@@ -4,12 +4,35 @@
 #
 #    pip-compile --output-file=requirements/requirements.txt requirements/requirements.in
 #
-click==7.1.2              # via flask
-flask==1.1.2              # via -r requirements/requirements.in
-itsdangerous==1.1.0       # via flask
-jinja2==2.11.2            # via flask
-markdown==3.3.3           # via -r requirements/requirements.in
-markupsafe==1.1.1         # via jinja2
-pytz==2020.4              # via tzlocal
-tzlocal==2.1              # via -r requirements/requirements.in
-werkzeug==1.0.1           # via flask
+bleach==3.2.2
+    # via mdx-linkify
+click==7.1.2
+    # via flask
+flask==1.1.2
+    # via -r requirements/requirements.in
+itsdangerous==1.1.0
+    # via flask
+jinja2==2.11.2
+    # via flask
+markdown==3.3.3
+    # via
+    #   -r requirements/requirements.in
+    #   mdx-linkify
+markupsafe==1.1.1
+    # via jinja2
+mdx-linkify==2.1
+    # via -r requirements/requirements.in
+packaging==20.8
+    # via bleach
+pyparsing==2.4.7
+    # via packaging
+pytz==2020.5
+    # via tzlocal
+six==1.15.0
+    # via bleach
+tzlocal==2.1
+    # via -r requirements/requirements.in
+webencodings==0.5.1
+    # via bleach
+werkzeug==1.0.1
+    # via flask