update navigate-related help and function docs

doc/help/commands.asciidoc

@@ -480,6 +480,9 @@ This tries to automatically click on typical _Previous Page_ or _Next Page_ link
 * +*-b*+, +*--bg*+: Open in a background tab.
 * +*-w*+, +*--window*+: Open in a new window.
 
+==== count
+For `increment` and `decrement`, the number to change the URL by. For `up`, the number of levels to go up in the URL.
+
 [[open]]
 === open
 Syntax: +:open [*--implicit*] [*--bg*] [*--tab*] [*--window*] ['url']+

qutebrowser/browser/commands.py

@@ -503,6 +503,8 @@ class CommandDispatcher:
             tab: Open in a new tab.
             bg: Open in a background tab.
             window: Open in a new window.
+            count: How much to increment or decrement the URL by, or number of
+                   levels to go up in the current URL.
         """
         # save the pre-jump position in the special ' mark
         self.set_mark("'")

qutebrowser/browser/navigate.py

@@ -36,6 +36,7 @@ def incdec(url, count, inc_or_dec):
 
     Args:
         url: The current url.
+        count: How much to increment or decrement by.
         inc_or_dec: Either 'increment' or 'decrement'.
         tab: Whether to open the link in a new tab.
         background: Open the link in a new background tab.
@@ -54,6 +55,7 @@ def path_up(url, count):
 
     Args:
         url: The current url.
+        count: The number of levels to go up in the url.
     """
     path = url.path()
     if not path or path == '/':

qutebrowser/utils/urlutils.py

@@ -527,6 +527,7 @@ def incdec_number(url, incdec, count=1, segments=None):
     Args:
         url: The current url
         incdec: Either 'increment' or 'decrement'
+        count: The number to increment or decrement by
         segments: A set of URL segments to search. Valid segments are:
                   'host', 'path', 'query', 'anchor'.
                   Default: {'path', 'query'}