Merge branch 'update-09-23-2020' into 'master'

Say debian jesse support ends

See merge request zcash-docs/zcash-docs!223

source/rtd_pages/Debian-Ubuntu-build.md

@@ -1,5 +1,8 @@
 # Building Zcashd & Zcash-cli on Debian/Ubuntu
 
+*Please upgrade!* [End of Debian Jessie support is on October 1st 2020.](https://forum.zcashcommunity.com/t/end-of-debian-jessie-support-is-on-october-1st-2020/37313)
+
+
 Zcashd & Zcash-cli are [officially supported](https://zcash.readthedocs.io/en/latest/rtd_pages/supported_platform_policy.html) for Debian/Ubuntu. Since Debian/Ubuntu is the best supported platform, we recommend running Zcashd & Zcash-cli on Debian/Ubuntu if possible. 
 
 ## Instructions

source/rtd_pages/zcashd.md

@@ -11,7 +11,7 @@ Zcashd & Zcash-cli are maintained by Electric Coin Company (the founding team fo
 
 * [Docker](https://hub.docker.com/r/electriccoinco/zcashd) (containerized DebianOS)
 
-* [Debian/Ubuntu](https://zcash.readthedocs.io/en/latest/rtd_pages/Debian-Ubuntu-build.html) ([officially](https://zcash.readthedocs.io/en/latest/rtd_pages/supported_platform_policy.html#supported-platform-policy) supported)
+* [Debian/Ubuntu](https://zcash.readthedocs.io/en/latest/rtd_pages/Debian-Ubuntu-build.html) ([officially](https://zcash.readthedocs.io/en/latest/rtd_pages/supported_platform_policy.html#supported-platform-policy) supported) *[Debian Jessie support ends on Oct 1st 2020.](https://forum.zcashcommunity.com/t/end-of-debian-jessie-support-is-on-october-1st-2020/37313)*
 
 * [Other Linux Systems](https://zcash.readthedocs.io/en/latest/rtd_pages/Linux-misc-build.html) ("best-effort" supported)