Retire Senthilnathan Natarajan from fabric maintainers (#4935)

Policy from the contribution guide:
Maintainers may be removed for prolonged inactivity (e.g. 3 or more months with no review comments).

Signed-off-by: David Enyeart <enyeart@us.ibm.com>

MAINTAINERS.md

@@ -12,7 +12,6 @@ See [the documentation on Maintainers](https://hyperledger-fabric.readthedocs.io
 | Artem Barger            | [c0rwin][c0rwin] | c0rwin | <artem@bargr.net>
 | Dave Enyeart            | [denyeart][denyeart] | dave.enyeart | <enyeart@us.ibm.com>
 | Manish Sethi            | [manish-sethi][manish-sethi] | manish-sethi | <manish.sethi@gmail.com>
-| Senthilnathan Natarajan | [cendhu][cendhu] | Senthil1 | <cendhu@gmail.com>
 | Tatsuya Sato            | [satota2][satota2] | satota2 | <tatsuya.sato.so@hitachi.com>
 | Yacov Manevich          | [yacovm][yacovm] | yacovm | <yacov.manevich@gmail.com>
 | Yoav Tock               | [tock-ibm][tock-ibm] | tock-ibm | <tock@il.ibm.com>
@@ -52,6 +51,7 @@ See [the documentation on Maintainers](https://hyperledger-fabric.readthedocs.io
 | Kostas Christidis | [kchristidis][kchristidis] | kostas | <kostas@gmail.com>
 | Matthew Sykes | [sykesm][sykesm] | sykesm | <matthew.sykes@gmail.com>
 | Pam Andrejko | [pamandrejko][pamandrejko] | pandrejko | <pama@ibm.com>
+| Senthilnathan Natarajan | [cendhu][cendhu] | Senthil1 | <cendhu@gmail.com>
 | Sheehan Anderson | [srderson][srderson] | sheehan | <sranderson@gmail.com>
 | Srinivasan Muralidharan | [muralisrini][muralisrini] | muralisr | <srinivasan.muralidharan99@gmail.com>
 | Tamas Blummer | [tamasblummer][tamasblummer] | tamas | <tamas@digitalasset.com>