Bump lxml from 4.6.1 to 4.6.2 in /docs

Bumps [lxml](https://github.com/lxml/lxml) from 4.6.1 to 4.6.2.
- [Release notes](https://github.com/lxml/lxml/releases)
- [Changelog](https://github.com/lxml/lxml/blob/master/CHANGES.txt)
- [Commits](lxml/lxml@lxml-4.6.1...lxml-4.6.2)

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

docs/requirements.txt

@@ -12,7 +12,7 @@ docutils==0.16            # via sphinx
 idna==2.10                # via requests
 imagesize==1.2.0          # via sphinx
 jinja2==2.11.2            # via sphinx
-lxml==4.6.1               # via -r requirements.in
+lxml==4.6.2               # via -r requirements.in
 markupsafe==1.1.1         # via jinja2
 packaging==20.4           # via sphinx
 pyenchant==3.1.1          # via sphinxcontrib-spelling