[dev] README updated

Author: mkozhukh

README.md

@@ -9,8 +9,8 @@ Converts JSON config to SQL Query
   "rules": [{
     "field":"age",
     "condition":{
-      "rule": "less",
-      "value": 42
+      "type": "less",
+      "filter": 42
     } 
   },{
     "field":"region",
@@ -19,3 +19,55 @@ Converts JSON config to SQL Query
 }
 ```
 
+### Supported operations ( type )
+
+- equal
+- notEqual
+- contains
+- notContains
+- lessOrEqual
+- greaterOrEqual
+- less
+- notBetween
+- between
+- greater
+- beginsWith
+- notBeginsWith
+- endsWith
+- notEndsWith
+
+### nesting
+
+Blocks can be nested like next
+
+```json
+{
+  "glue": "and",
+  "rules": [
+    ruleA,
+    {
+      "glue": "or",
+      "rules": [
+        ruleC,
+        ruleD
+      ] 
+    }
+  ] 
+}
+```
+
+### between / notBeetween
+
+For those operations, both start and end values can be provided
+
+```json
+{
+    "field":"age",
+    "condition":{
+      "type": "between",
+      "filter": { "start": 10, "end": 99 }
+    } 
+  }
+```
+
+if only *start* or *end* provided, the operation will change to *less* or *greater* automatically