Feature/examples (#261)

* Feature: Ocean-subgraph javascript and python examples

* Feature: Ocean-subgraph example add credit

* Rename js example file

* Feature: Add ocean-subgraph python example

examples/javascript/get-all-pools.md

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+## Ocean-subgraph javascript example
+
+Query to get all datatoken pools
+
+```javascript
+const axios = require('axios');
+
+const BASE_URL = 'https://subgraph.rinkeby.oceanprotocol.com';
+const SUBGRAPHS_QUERY_ROUTE = '/subgraphs/name/oceanprotocol/ocean-subgraph';
+
+const url = BASE_URL + SUBGRAPHS_QUERY_ROUTE;
+
+async function getAllPoolDatatokenAddresses(url) {
+    const requestBody = { query: '{ pools(first:1000, orderBy: oceanReserve, orderDirection: desc) { id valueLocked name consumePrice totalShares symbol cap datatokenAddress tokens { id balance name symbol  } } }' };
+    const response = await axios.post(url, requestBody).catch((error) => {
+        const { status, statusText, data } = error.response;
+        console.error('Error getting data from subgraph: ', status, statusText, data);
+        throw new Error(statusText);
+    });
+    const { data: { data: { pools }, }, } = response;
+    return pools.filter((pool) => pool.datatokenAddress).map((pool) => pool.datatokenAddress);
+}
+
+getAllPoolDatatokenAddresses(url).then(result => {
+    console.log(result)
+});
+
+```
+
+
+### Credits
+- German Navarro - Github user: gmanavarro - Discord user: Naga#2072
+- Axel Diaz - Github user: axeldiaz10 - Discord user: axeldiaz10#0085
+- Juan Arrillaga - Github user: jarrillaga - Discord user: juanarri#3482

examples/python/get-orders.md

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+## Ocean-subgraph python example
+
+Query to fetch all datatoken `Transfer` events
+
+```python
+import requests
+import json
+
+datatoken_address = "0x00b43f5905ff736526294ac6de52d1dcd35821c9"
+base_url = "https://subgraph.rinkeby.oceanprotocol.com"
+route = "/subgraphs/name/oceanprotocol/ocean-subgraph"
+url = base_url + route
+
+query = """{{
+    tokenOrders(where:{{datatokenId:"{0}"}}, first: 5, orderBy: timestamp, orderDirection: desc) {{
+        id
+        consumer {{id}}
+        payer {{id}}
+        serviceId
+        marketFeeCollector {{id}}
+        marketFee
+        tx
+        block
+    }}
+    }}""".format(datatoken_address)
+
+headers = {"Content-Type": "application/json"}
+
+payload = json.dumps({"query": query})
+response = requests.request("POST", url, headers=headers, data=payload)
+result = json.loads(response.text)
+
+
+print(result)
+```

examples/python/global-statistics.md

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+
+## Ocean-subgraph python example
+
+Query global statistics like `totalValueLocked`, `totalOceanLiquidity`, `orderCount`, etc.
+
+```python
+import requests
+import json
+
+base_url = "https://subgraph.rinkeby.oceanprotocol.com"
+route = "/subgraphs/name/oceanprotocol/ocean-subgraph"
+url = base_url + route
+
+query = """
+{
+globals {
+  id
+  totalValueLocked
+  totalOceanLiquidity
+  totalSwapVolume
+  totalOrderVolume
+  orderCount
+  poolCount
+}
+}"""
+
+headers = {"Content-Type": "application/json"}
+
+payload = json.dumps({"query": query})
+response = requests.request("POST", url, headers=headers, data=payload)
+result = json.loads(response.text)
+
+print(result)
+```

examples/python/list-datatokens.md

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+## Ocean-subgraph python example
+
+Query to fetch all datatoken "Transfer" events
+
+```python
+import requests
+import json
+
+datatoken_address = "0xd0a8540db74bab9ef5847a2424ee3fc26b4518a5"
+base_url = "https://subgraph.rinkeby.oceanprotocol.com"
+route = "/subgraphs/name/oceanprotocol/ocean-subgraph"
+url = base_url + route
+
+query_string = """{{tokenTransactions(skip: {0}, first: {1},
+                where:{{event:"Transfer",datatokenAddress:"{2}"}},
+                orderBy: timestamp, orderDirection: asc) {{
+                id,
+                event
+                timestamp
+                block
+        }}}}"""
+
+headers = {"Content-Type": "application/json"}
+
+skip = 0
+limit = 1000
+result = []
+while True:
+    query = query_string.format(skip, limit, datatoken_address)
+    payload = json.dumps({"query": query})
+    response = requests.request("POST", url, headers=headers, data=payload)
+    if response.status_code != 200:
+        break
+    data = json.loads(response.text)
+    if (len(data["data"]["tokenTransactions"])) == 0:
+        break
+    result.append(data["data"])
+    skip = skip + limit
+
+print(result)
+```