[HUDI-7089] Add docs for new features in 1.0.0-beta

[codope]

Change Logs

• Update CREATE INDEX syntax and show example fo creating functional index in SQL DDL page.
• Update about non-blocking concurrency control in concurrency mode page.
• Update flink quickstart page with an example of new concurrency mode.
• Update timeline page with details about LSM timeline.

Impact

Add docs for new features in 1.0.0-beta1.

Risk level (write none, low medium or high below)

none

Documentation Update

Describe any necessary documentation update if there is any new feature, config, or user-facing change

• The config description must be updated if new configs are added or the default value of the configs are changed
• Any new feature or user-facing change requires updating the Hudi website. Please create a Jira ticket, attach the
  ticket number here and follow the instruction to make
  changes to the website.

Contributor's checklist

• Read through contributor's guide
• Change Logs and Impact were stated clearly
• Adequate tests were added if applicable
• CI passed

[bhasudha]

LGTM