add docs footer, edit on github link

src/components/DocFooter.jsx

@@ -0,0 +1,21 @@
+import React from 'react'
+import PropTypes from 'prop-types'
+import styles from './DocFooter.module.scss'
+
+const DocFooter = ({ post }) => (
+    <footer className={styles.footer}>
+        <a
+            href={`https://github.com/oceanprotocol/docs/blob/master/content/${
+                post.parent.relativePath
+            }`}
+        >
+            Edit on GitHub
+        </a>
+    </footer>
+)
+
+DocFooter.propTypes = {
+    post: PropTypes.object.isRequired
+}
+
+export default DocFooter

src/components/DocFooter.module.scss

@@ -0,0 +1,17 @@
+@import 'variables';
+
+.footer {
+    margin-top: $spacer;
+    padding-top: $spacer;
+    margin-bottom: $spacer;
+    padding-bottom: $spacer;
+    border-top: .1rem solid $brand-grey-lighter;
+    font-size: $font-size-small;
+    text-align: center;
+
+    a {
+        font-family: $font-family-button;
+        text-transform: uppercase;
+        color: $brand-grey-light;
+    }
+}

src/templates/Doc.jsx

@@ -5,6 +5,7 @@ import Layout from '../components/Layout'
 import Content from '../components/Content'
 import HeaderSection from '../components/HeaderSection'
 import Sidebar from '../components/Sidebar'
+import DocFooter from '../components/DocFooter'
 import styles from './Doc.module.scss'
 
 export default class DocTemplate extends Component {
@@ -57,6 +58,8 @@ export default class DocTemplate extends Component {
                                         __html: post.html
                                     }}
                                 />
+
+                                <DocFooter post={post} />
                             </article>
                         </main>
                     ) : (
@@ -74,6 +77,8 @@ export default class DocTemplate extends Component {
                                     __html: post.html
                                 }}
                             />
+
+                            <DocFooter post={post} />
                         </article>
                     )}
                 </Content>
@@ -94,6 +99,7 @@ export const pageQuery = graphql`
             id
             excerpt
             html
+            fileAbsolutePath
             frontmatter {
                 title
                 description
@@ -101,6 +107,7 @@ export const pageQuery = graphql`
             fields {
                 section
             }
+            ...PageFooter
         }
 
         allSectionsYaml {
@@ -113,4 +120,12 @@ export const pageQuery = graphql`
             }
         }
     }
+
+    fragment PageFooter on MarkdownRemark {
+        parent {
+            ... on File {
+                relativePath
+            }
+        }
+    }
 `