add intro and feature list

README.md

@@ -4,6 +4,48 @@
 
 Elasticsearch CLI
 
+## Introduction
+
+This is a handy cli tool which interfaces to an elasticsearch cluster
+(or two of them if you're using cross cluster replication). It is a
+work-in-progress project yet, things might change occasionally. Expect
+a stable release once we reach major version 1.0.0.
+
+Features:
+
+- Configuration of cluster credentials using environment vars or
+  config file. Multiple clusters can be configured. `esctl cluster ls`
+  shows which one is reachable.
+- Shell completion support (bash, zsh and fish). Put this into your
+  rc: `source <(esctl completion bash)`.
+- Cluster settings can be viewed and modified.
+- 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
+  recursive searches like: `(cond1 AND cond2) OR (cond3 OR cond4)`.
+- Cross cluster replication (ccr): view, pause, resume, delete
+  replication. You can also manage follower configuration.
+- Index management: manage aliases, create, modify, delete indices,
+  display field mappings etc.
+- Node management: only list nodes yet.
+- Shard management: only list shards yet.
+- Snapshot management: only list snapshots yet.
+- Role management: only list roles yet. There's also a `role diff`
+  subcommand, which is for internal use. It can be used to verify if
+  role defs in a CSV match the deployed roles.
+- Repl: this is an interactive REPL (read eval print loop) towards the
+  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.
+- 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
+  experiments:
+  ```console
+  esctl doc add -i foo2 '{"title":"curry in a hurry", "message":"australian thai"}'
+  ```
+
 ## Usage
 
 Command tree:
@@ -91,10 +133,6 @@ can omit `-c ...`.
 If you want to  work on a specific cluster, specify  its name with the
 global `-C` option.
 
-## Introduction
-
-FIXME
-
 ## Installation
 
 The tool does not have any dependencies.  Just download the binary for