Fix typo in documentation "jdkfile" (actions#167)

Author: dmitry-shibanov

docs/advanced-usage.md

@@ -75,7 +75,7 @@ steps:
     wget -O $RUNNER_TEMP/java_package.tar.gz $download_url
 - uses: actions/setup-java@v2
   with:
-    distribution: 'jdkFile'
+    distribution: 'jdkfile'
     jdkFile: ${{ runner.temp }}/java_package.tar.gz
     java-version: '11.0.0'
     architecture: x64

docs/switching-to-v2.md

@@ -16,7 +16,7 @@ steps:
 **General recommendation** — configure CI with the same distribution that is used on your local dev machine.
 
 ## Installing custom Java distribution from local file
-Since the `distribution` input is required in V2, you should specify it using `jdkFile` to continue installing Java from a local file on the runner
+Since the `distribution` input is required in V2, you should specify it using `jdkfile` to continue installing Java from a local file on the runner
 ```yaml
 steps:
 - run: |