schedule: adjust Node.js 16 End-of-Life (#752)

Update schedule, README table and chart to reflect the change to
Node.js 16's End-of-Life date to September 11, 2023.

Move Node.js 17 to End-of-Life table.

Refs: nodejs/TSC#1222
Refs: nodejs/nodejs.org#4629

README.md

@@ -5,8 +5,7 @@
 | Release  | Status              | Codename     |Initial Release | Active LTS Start | Maintenance Start | End-of-life               |
 | :--:     | :---:               | :---:        | :---:          | :---:            | :---:             | :---:                     |
 | [14.x][] | **Maintenance**     | [Fermium][]  | 2020-04-21     | 2020-10-27       | 2021-10-19        | 2023-04-30                |
-| [16.x][] | **Active LTS**      | [Gallium][]  | 2021-04-20     | 2021-10-26       | 2022-10-18        | 2024-04-30                |
-| [17.x][] | **Maintenance**     |              | 2021-10-19     | -                | 2022-04-01        | 2022-06-01                |
+| [16.x][] | **Active LTS**      | [Gallium][]  | 2021-04-20     | 2021-10-26       | 2022-10-18        | [2023-09-11][nodejs16eol] |
 | [18.x][] | **Current**         |              | 2022-04-19     | 2022-10-25       | 2023-10-18        | 2025-04-30                |
 | 19.x     | **Pending**         |              | 2022-10-18     | -                | 2023-04-01        | 2023-06-01                |
 | 20.x     | **Pending**         |              | 2023-04-18     | 2023-10-24       | 2024-10-22        | 2026-04-30                |
@@ -57,6 +56,7 @@ that are not End-of-Life.
 | [12.x][] | **End-of-Life** | [Erbium][]|    2019-04-23   |    2019-10-21    |       2020-11-30      |  2022-04-30 |
 | [13.x][] | **End-of-Life** |           |    2019-10-22   |         -        |                       |  2020-06-01 |
 | [15.x][] | **End-of-Life** |           |    2020-10-20   |         -        |                       |  2021-06-01 |
+| [17.x][] | **End-of-Life** |           |    2021-10-19   |         -        |                       |  2022-06-01 |
 
 ## Mandate
 
@@ -149,6 +149,8 @@ the discretion of the Release working group.
 [Erbium]: https://nodejs.org/download/release/latest-erbium/
 [Fermium]: https://nodejs.org/download/release/latest-fermium/
 [Gallium]: https://nodejs.org/download/release/latest-gallium/
+[JSON]: schedule.json
+[nodejs16eol]: https://nodejs.org/en/blog/announcements/nodejs16-eol/
 [4.x]: https://nodejs.org/download/release/latest-v4.x/
 [5.x]: https://nodejs.org/download/release/latest-v5.x/
 [6.x]: https://nodejs.org/download/release/latest-v6.x/
@@ -164,7 +166,6 @@ the discretion of the Release working group.
 [16.x]: https://nodejs.org/download/release/latest-v16.x/
 [17.x]: https://nodejs.org/download/release/latest-v17.x/
 [18.x]: https://nodejs.org/download/release/latest-v18.x/
-[JSON]: schedule.json
 
 The working group members are the union of the LTS, Releasers
 and CITGM team members listed below.

schedule.json

@@ -87,7 +87,7 @@
     "start": "2021-04-20",
     "lts": "2021-10-26",
     "maintenance": "2022-10-18",
-    "end": "2024-04-30",
+    "end": "2023-09-11",
     "codename": "Gallium"
   },
   "v17": {