Add some text to the README and a screenshot

[github-actions[bot]]

Images automagically compressed by Calibre's image-actions ✨

Compression reduced images by 27.9%, saving 153.67 KB

Filename	Before	After	Improvement
screenshot.png	191.61 KB	129.78 KB	-32.3%
static/images/logs-and-metrics/grafana-prometheus.png	40.79 KB	33.97 KB	-16.7%
static/images/solr-synonyms/analysis-ui.png	177.26 KB	110.41 KB	-37.7%
themes/jorgelbg/images/screenshot.png	52.33 KB	51.19 KB	-2.2%
themes/jorgelbg/images/tn.png	29.54 KB	28.00 KB	-5.2%
themes/jorgelbg/static/android-chrome-192x192.png	8.41 KB	6.76 KB	-19.7%
themes/jorgelbg/static/android-chrome-512x512.png	16.60 KB	13.53 KB	-18.5%
themes/jorgelbg/static/apple-touch-icon.png	6.23 KB	4.80 KB	-23.0%
themes/jorgelbg/static/favicon-16x16.png	1,014 bytes	575 bytes	-43.3%
themes/jorgelbg/static/favicon-32x32.png	1.69 KB	1.05 KB	-37.8%
themes/jorgelbg/static/images/avatar.png	4.86 KB	3.20 KB	-34.1%
themes/jorgelbg/static/images/avatar@2x.png	14.82 KB	9.38 KB	-36.7%
themes/jorgelbg/static/mstile-150x150.png	5.84 KB	4.70 KB	-19.6%

Some images were already optimised

* `content/posts/2019/rename-kibana-index-patterns/export-ui.png` * `content/posts/2019/rename-kibana-index-patterns/import-ui.png` * `content/posts/2019/rename-kibana-index-patterns/kibana.png` * `static/images/app-version-in-grafana/final-result.png` * `static/images/app-version-in-grafana/series-override.png` * `static/images/avatar.png` * `static/images/avatar@2x.png` * `static/images/dissect-tester-announcement/log-patterns.png` * `static/images/dissect-tester-announcement/screenshot.png` * `static/images/elasticsearch-indices-grafana/filter-all-the-things.jpg` * `static/images/elasticsearch-indices-grafana/grafana-example-query.png` * `static/images/elasticsearch-indices-grafana/original-query-profile.png` * `static/images/elasticsearch-indices-grafana/periodic-query-time-spike.png` * `static/images/elasticsearch-indices-grafana/query-with-filters-profile.png` * `static/images/es-watcher-ml-alert/final-alert-example.png`