[CALCITE-6098] Update LICENSE and NOTICE for Jekyll website template

The NOTICE file contains the following statement:
```
The web site includes files generated by Jekyll.
```

However, there is nothing in the LICENSE of Jekyll, that requires such
attribution.

According to the instructions of composing the NOTICE file for ASF
projects we shouldn't add anything in there that is not legally
required.

The files comprisings the template of the web site i.e.,
site/_includes,
site/_layouts,
site/_sass,
site/css

were copied and slightly adapted from the ORC repository, which in turn
copied the template from the Jekyll repository. There have been various
small additions in the orignal template (some .html files under the
respective directories are completely new) which could potentially
licensed under AL2 but it would complicate the LICENSE documentation
without significant gain. It's better if the consumers of the source
distribution know that this is a Jekyll template licensed under MIT.

Close apache#3510

LICENSE

@@ -182,6 +182,15 @@ Additional License files can be found in the 'licenses' folder located in the sa
 
 MIT
 * font-awesome:font-awesome-code:4.2.0
+site/_sass/_font-awesome.scss
 * cobyism:gridism:
+site/_sass/_gridism.scss
 * jekyll:jekyll:
+site/css/screen.scss
+site/_includes/*.html
+site/_layouts/*.html
+site/news/releases/index.html
+site/_sass/_mixins.scss
+site/_sass/_pygments.scss
 * normalize:normalize:3.0.2
+site/_sass/_normalize.scss

NOTICE

@@ -8,5 +8,3 @@ This product is based on source code originally developed
 by DynamoBI Corporation, LucidEra Inc., SQLstream Inc. and others
 under the auspices of the Eigenbase Foundation
 and released as the LucidDB project.
-
-The web site includes files generated by Jekyll.