Fix a couple of typos (#748)

* Add name to contributors in preface

* Add missing word

* Remove extraneous word

"being in used" -> "being used"

07_payment_channels.asciidoc

@@ -106,7 +106,7 @@ So the full identifier for Rene's node would be:
 
 [TIP]
 ====
-The alias of Rene's node is +ln.rene-pickhardt.de+ however this name exists just for better readability every node operator can announce an alias at free will and actually there is no mechanism that prevents node operators to select an alias that is already being in used. Thus in order to refer to a node one must use the +NodeID@Address:Port+ schema.
+The alias of Rene's node is +ln.rene-pickhardt.de+ however this name exists just for better readability every node operator can announce an alias at free will and actually there is no mechanism that prevents node operators to select an alias that is already being used. Thus in order to refer to a node one must use the +NodeID@Address:Port+ schema.
 ====
 
 The identifier above is often encoded in a QR code, making it easier for users to scan, if they want to connect their own node to the specific node identified by that address.

preface.asciidoc

@@ -185,6 +185,7 @@ Following is an alphabetically sorted list of all the GitHub contributors, inclu
 * Eduardo Lima III (@elima-iii)
 * Emilio Norrmann (@enorrmann)
 * Francisco Calderón (@grunch)
+* François Degros (@fdegros)
 * Giovanni Zotta (@GiovanniZotta)
 * Gustavo Silva (@GustavoRSSilva)
 * Haoyu Lin (@HAOYUatHZ)