chore: satisfy flake8

mkdocs_semiliterate/plugin.py

@@ -112,7 +112,7 @@ is checked for `{! ... !}`.
             raise EOFError(errmsg)
         filename = body_match['fn']
         gitextract = False
-        dq_doc = """ md
+        r""" md
 ### Double-quoted filenames and Git extraction
 
 Standard Python escape sequences in double-quoted filenames are interpreted
@@ -139,7 +139,8 @@ include content from that file. For example, you could write
 to extract content starting after the `### install` line from the
 `mkdocs.yml` file in the Git commit of this repository
 tagged `0.1.0`. This feature is primarily useful if you are documenting the
-development or changes to a project over time, and want to be sure that
+development or changes to a project over time, or are documenting a feature
+in a specific past release of your project, and want to be sure that
 material included in your documentation does _not_ change as the project
 progresses. (This behavior is as opposed to the usual case, in which you want
 your documentation to incorporate the most up-to-date version of extracted