Updated documentation

README.md

@@ -1,2 +1,72 @@
 # xml-sitemap-url-scraper
-Scrapes all URLs from XML sitemaps and returns them as an array. Includes nested sitemaps.
+Call the function with an array of one or more XML sitemap urls. All sitemap urls provided in this array must not be compressed. Compressed sitemaps are only supported when nested under `<sitemapindex>` tags.
+
+_GOOD:_ https://www.example.com/sitemap.xml
+
+_BAD:_  https://www.example.com/sitemap.xml.gz
+
+**Returns** a promise that resolves with an array of all URLs from those sitemaps
+
+**Install**
+
+```
+npm install --save xml-sitemap-url-scraper
+```
+
+**Example**
+
+```
+const { sitemapUrlScraper } = require("xml-sitemap-url-scraper");
+
+let sitemapUrls = [
+    "https://www.example.com/sitemap.xml"
+]
+
+let urls = sitemapUrlScraper(sitemapUrls);
+
+urls.then(result => {
+    console.log("Returned URLs: ", result);
+})
+.catch(err => {
+    console.log(err);
+})
+```
+
+**Example Output**
+
+```
+Returned URLs:  [ 'https://www.example.com/page_one',
+  'https://www.example.com/page_two' ]
+```
+
+## Nested Sitemaps in `<sitemapindex>` tags
+Nested sitemaps will automatically be traversed, and their urls will be included in the final output array. This currently only supports 1 level of nesting.
+
+**Exmaple of nested sitemaps**
+
+```
+<sitemapindex xmlns="https://www.example.com/schemas/sitemap/0.84">
+    <sitemap>
+    <loc>https://www.example.com/edu/sitemap.xml</loc>
+    </sitemap>
+    <sitemap>
+    <loc>https://www.example.com/gmail/sitemap.xml</loc>
+    </sitemap>
+</sitemapindex>
+```
+
+## Compressed Sitemaps
+Child sitemaps that are nested inside `<sitemapindex>` tags will be decompressed, and their urls will be included in the final output array. Compressed sitemaps are processed sequentially to avoid memory and CPU load issues. This function may take a long time to execute if there is a significant number of compressed sitemaps being scraped.
+
+**Example of compressed sitemaps**
+
+```
+<sitemapindex xmlns="https://www.example.com/schemas/sitemap/0.84">
+    <sitemap>
+    <loc>https://www.example.com/edu/sitemap.xml.gz</loc>
+    </sitemap>
+    <sitemap>
+    <loc>https://www.example.com/gmail/sitemap.xml.gz</loc>
+    </sitemap>
+</sitemapindex>
+```