Unify README.md and docs/_index.md (#5380)

Signed-off-by: Doğukan Teber <dogukanteber1@hotmail.com>

README.md

@@ -39,6 +39,9 @@ should read:
 1. [Getting started with Cortex](https://cortexmetrics.io/docs/getting-started/)
 1. [Information regarding configuring Cortex](https://cortexmetrics.io/docs/configuration/)
 
+There are also individual [guides](https://cortexmetrics.io/docs/guides/) to many tasks.
+Please review the important [security advice](https://cortexmetrics.io/docs/guides/security/) before deploying.
+
 For a guide to contributing to Cortex, see the [contributor guidelines](https://cortexmetrics.io/docs/contributing/).
 
 ## Further reading

tools/website/web-pre.sh

@@ -18,7 +18,7 @@ cp -r code-of-conduct.md CHANGELOG.md ${OUTPUT_CONTENT_DIR}
 cp GOVERNANCE.md ${OUTPUT_CONTENT_DIR}/contributing/governance.md
 cp images/* ${WEBSITE_DIR}/static/images
 
-# Add headers to special CODE_OF_CONDUCT.md and CHANGELOG.md files.
+# Add headers to special CODE_OF_CONDUCT.md, CHANGELOG.md and README.md files.
 echo "$(cat <<EOT
 ---
 title: Code of Conduct
@@ -52,6 +52,24 @@ EOT
 )" > ${OUTPUT_CONTENT_DIR}/contributing/governance.md
 tail -n +2 GOVERNANCE.md >> ${OUTPUT_CONTENT_DIR}/contributing/governance.md
 
+echo "$(cat <<EOT
+---
+title: "Documentation"
+linkTitle: "Documentation"
+weight: 1
+menu:
+  main:
+    weight: 1
+---
+EOT
+)" > ${OUTPUT_CONTENT_DIR}/_index.md
+
+# Ignore the header and some of the badges.
+head -6 README.md | tail +2 >> ${OUTPUT_CONTENT_DIR}/_index.md
+
+# Ignore another header and write the rest of the file.
+tail +12 README.md >> ${OUTPUT_CONTENT_DIR}/_index.md
+
 ALL_DOC_CONTENT_FILES=`echo "${OUTPUT_CONTENT_DIR}/**/*.md ${OUTPUT_CONTENT_DIR}/*.md"`
 for file in $(find ${OUTPUT_CONTENT_DIR} -name '*.md')
 do