[DOC] Clarify ES Version compatibility.

Author: jbaiera

docs/src/reference/asciidoc/core/intro/requirements.adoc

@@ -23,7 +23,7 @@ java version "1.8.0_45"
 [[requirements-es]]
 === {es}
 
-version *1.X* or higher, though we *highly* recommend using the latest Elasticsearch (currently {es-v}) is needed to run {es}. Using a lower version is not possible as {eh} uses new features added in 1.X for distributed, parallel interactions with {es}. We strongly recommend using the latest, stable version of Elasticsearch.
+We *highly* recommend using the latest Elasticsearch (currently {es-v}), but {eh} is also backwards compatible with the *1.X* and *2.X* versions of {es}. {es} versions lower than 1.X are not supported as {eh} uses new features added in 1.X for distributed parallel interactions with {es}. We strongly recommend using the latest, stable version of Elasticsearch.
 
 The {es} version is shown in its folder name:
 
@@ -33,7 +33,7 @@ $ ls
 elasticsearch-{es-v}
 ----
 
-If {es} is running (locally or remotely), one can find out through REST its version:
+If {es} is running (locally or remotely), one can find out its version through REST:
 
 ["source","js",subs="attributes"]
 ----