less, more: Update page up/down shortcut (#1038)

- Previous shortcut (`D`/`d`) refers to scrolling half of a page, not a full page

pages/common/less.md

@@ -10,7 +10,7 @@
 
 - Page up / down:
 
-`d (next), D (previous)`
+`<Space> (next), b (previous)`
 
 - Go to start / end of file:
 

pages/common/more.md

@@ -10,7 +10,7 @@
 
 - Page down:
 
-`d (next)`
+`<Space> (next)`
 
 - Search for a string: