[MINOR] Remove instructions for MD5 checksum generation

On par with new Apache policy
diff --git a/PMC.md b/PMC.md
index e81b9ea..f61d75e 100644
--- a/PMC.md
+++ b/PMC.md
@@ -43,9 +43,7 @@
 (http://apache.org/dev/release-signing.html#openpgp-ascii-detach-sig)
     * `gpg --armor --output apache-predictionio-0.13.0-rc1.tar.gz.asc
   --detach-sig apache-predictionio-0.13.0-rc1.tar.gz`
-7. Generate MD5 and SHA512 checksums for the release candidate.
-    * `gpg --print-md MD5 apache-predictionio-0.13.0-rc1.tar.gz >
-  apache-predictionio-0.13.0-rc1.tar.gz.md5`
+7. Generate SHA512 checksums for the release candidate.
     * `gpg --print-md SHA512 apache-predictionio-0.13.0-rc1.tar.gz >
   apache-predictionio-0.13.0-rc1.tar.gz.sha512`
 8. Run `./make-distribution.sh` and repeat steps 5 to 7 to create binary distribution release.
diff --git a/docs/manual/source/install/install-sourcecode.html.md.erb b/docs/manual/source/install/install-sourcecode.html.md.erb
index ac08009..6b9bd63 100644
--- a/docs/manual/source/install/install-sourcecode.html.md.erb
+++ b/docs/manual/source/install/install-sourcecode.html.md.erb
@@ -24,7 +24,8 @@
 
 ## Downloading Binary Distribution
 
-You can binary distribution for Apache PredictionIO® if you are building against
+You can use pre-built binary distribution for Apache PredictionIO® if you are
+building against
 
 * Scala 2.11.8
 * Spark 2.1.1