doc: remove duplicate lines from index.rst

doc/index.rst

@@ -27,10 +27,6 @@ c-lightning Documentation
    :maxdepth: 1
    :caption: Manpages
 
-   lightningd <lightningd.8.md>
-   lightningd-config <lightningd-config.5.md>
-   lightningd <lightningd.8.md>
-   lightningd-config <lightningd-config.5.md>
    lightningd <lightningd.8.md>
    lightningd-config <lightningd-config.5.md>
    lightning-autocleaninvoice <lightning-autocleaninvoice.7.md>
@@ -38,8 +34,6 @@ c-lightning Documentation
    lightning-cli <lightning-cli.1.md>
    lightning-close <lightning-close.7.md>
    lightning-connect <lightning-connect.7.md>
-   lightningd <lightningd.8.md>
-   lightningd-config <lightningd-config.5.md>
    lightning-decodepay <lightning-decodepay.7.md>
    lightning-delexpiredinvoice <lightning-delexpiredinvoice.7.md>
    lightning-delinvoice <lightning-delinvoice.7.md>