Update README.md

README.md

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+# Installing
+  ```go
+  go get github.com/adnanh/webhook
+  ```
+
+# Updating
+  ```go
+  go get -u github.com/adnanh/webhook
+  ```
+  
+# Adding hooks
+  Hooks are defined using JSON format. The hooks file must contain an array of JSON formatted hooks. Here is an example of a valid hooks file containing one hook. The hook will be triggered whenever a push to the master branch occurrs.
+  ```json
+  [
+    {
+      "id": "hook-1",
+      "command": "OS command to be executed when the hook gets triggered",
+      "cwd": "current working directory under which the specified command will be executed (optional, defaults to the directory where the binary resides)",
+      "secret": "secret key used to compute the hash of the payload (optional)",
+      "trigger-rule":
+      {
+        "match":
+        {
+          "parameter": "ref",
+          "value": "refs/heads/master"
+        }
+      }
+    }
+  ]
+  ```
+# Trigger rules
+### And
+*And rule* will evaluate to _true_, if and only if all of the sub rules evaluate to _true_.
+```json
+{ 
+"and": 
+  [
+    {
+      "match":
+      {
+        "parameter": "ref",
+        "value": "refs/heads/master"
+      }
+    },
+    {
+      "match":
+      {
+        "parameter": "repository.owner.name",
+        "value": "adnanh"
+      }
+    }
+  ]
+}
+```
+### Or
+*Or rule* will evaluate to _true_, if any of the sub rules evaluate to _true_.
+```json
+{ 
+"or": 
+  [
+    {
+      "match":
+      {
+        "parameter": "ref",
+        "value": "refs/heads/master"
+      }
+    },
+    {
+      "match":
+      {
+        "parameter": "ref",
+        "value": "refs/heads/development"
+      }
+    }
+  ]
+}
+```
+### Not
+*Not rule* will evaluate to _true_, if and only if the sub rule evaluate to _false_.
+```json
+{
+"not":
+  {
+    "match":
+    {
+      "parameter": "ref",
+      "value": "refs/heads/master"
+    }
+  }
+}
+```
+### Match
+*Match rule* will evaluate to _true_, if and only if the payload structure contains the key specified in the `parameter` value, contains same value as specified in the `value` value.
+*Please note:* due to technical limitations, _number_ and _boolean_ values in hooks file must be wrapped around with quotes.
+
+```json
+{
+  "match":
+  {
+    "parameter": "ref",
+    "value": "refs/heads/master"
+  }
+}
+```
+
+It is possible to specify the values deeper in the payload JSON object with the dot operator, and if a value of the specified key is an array, it's possible to index the array values by using the number instead of string as the key, as shown in a following example:
+```json
+{
+  "match":
+  {
+    "parameter": "commits.0.author.username",
+    "value": "adnanh"
+  }
+}
+```
+# Running
+In your `$GOPATH/bin` directory, you should have `webhook` binary.
+
+Simply running the binary using `./webhook` command, will start the webhook with the default options. That means the webhook will listen on all interfaces on port 9000. It will try to read and parse `hooks.json` file from the same directory where the binary is located, and it will log everything to stdout and the file `webhook.log`.
+
+To override any of these options, you can use the following command line flags:
+```bash
+-hooks="hooks.json": path to the json file containing defined hooks the webhook should serve
+-ip="": ip the webhook server should listen on
+-log="webhook.log": path to the log file
+-port=9000: port the webhook server should listen on
+```