Rename LICENSE.md to LICENSE, make the other changes that requires

The license text is not actually in Markdown, and adding the .md
extension actually makes it render a little differently than intended.

.pre-commit-config.yaml

@@ -26,10 +26,6 @@ repos:
     rev: v0.17.0
     hooks:
       - id: markdownlint
-        # The LICENSE.md must match the license text exactly for
-        # GitHub's autorecognition fu to work, so we should leave it
-        # alone.
-        exclude: LICENSE.md
         args:
           - --config=.mdl_config.json
   - repo: https://github.com/adrienverge/yamllint

CONTRIBUTING.md

@@ -8,8 +8,8 @@ of contribution, and don't want a wall of rules to get in the way of
 that.
 
 Before contributing, we encourage you to read our CONTRIBUTING policy
-(you are here), our [LICENSE](LICENSE.md), and our
-[README](README.md), all of which should be in this repository.
+(you are here), our [LICENSE](LICENSE), and our [README](README.md),
+all of which should be in this repository.
 
 ## Issues ##
 

README.md

@@ -4,7 +4,7 @@
 
 This is a generic skeleton project that can be used to quickly get a
 new [cisagov](https://github.com/cisagov) GitHub project started.
-This skeleton project contains [licensing information](LICENSE.md), as
+This skeleton project contains [licensing information](LICENSE), as
 well as [pre-commit hooks](https://pre-commit.com) and a [Travis
 CI](https://travis-ci.com) configuration appropriate for the major
 languages that we use.
@@ -19,7 +19,7 @@ details.
 
 ## License ##
 
-This project is in the worldwide [public domain](LICENSE.md).
+This project is in the worldwide [public domain](LICENSE).
 
 This project is in the public domain within the United States, and
 copyright and related rights in the work worldwide are waived through