add external pager support via ES_JSON_PAGER (#65)

README.md

@@ -23,6 +23,8 @@ Features:
 - Shell completion support (bash, zsh and fish). Put this into your
   rc: `source <(esctl completion bash)`.
 - Cluster settings can be viewed and modified.
+- Comprehensive cluster status.
+- Cluster reroute support.
 - Search: you can search indices using full text or by fields, select
   logical condition (OR, AND), use PIT, limit datetime (ES date math
   can be used), etc. It is however not yet possible to create
@@ -44,10 +46,12 @@ Features:
 - API  documentation   (`api  list`  and  `api   show  <path>`)  with
   interactive markdown pager for endpoint documentation.
 - Repl: this is an interactive REPL (read eval print loop) towards the
-  elasticsearch API. You can run API calls on the current selected
+  elasticsearch API.  You can  run API calls  on the  current selected
   cluster w/o the hassle to specify the whole url, credentials etc. It
-  has line editing and history support. If `jq` is installed output
-  JSON will be syntax highlighted.
+  has line  editing and history  support. If `jq` is  installed output
+  JSON will  be syntax  highlighted. A simple  internal pager  will be
+  used if output exceeds the terminal height. You can tweak this using
+  the `$ES_JSON_PAGER` environment variable (I'd recommend [fx](https://fx.wtf/)).
 - Doc support. You can put, delete and show docs for an index. Very
   handy if you want to play with it. Just create a new index:
   `esctl index create foo` and then insert docs into it for search