Docs: fix some typos and remove duplicate word

Author: sadielbartholomew

cf/data/data.py

@@ -4896,9 +4896,9 @@ def Units(self):
         >>> d = cf.Data([1, 2, 3], units='m')
         >>> d.Units
         <Units: m>
-        >>> d.Units = cf.Units('kilmetres')
+        >>> d.Units = cf.Units('kilometres')
         >>> d.Units
-        <Units: kilmetres>
+        <Units: kilometres>
         >>> d.Units = cf.Units('km')
         >>> d.Units
         <Units: km>
@@ -12045,7 +12045,7 @@ def to_memory(self):
     def transpose(self, axes=None, inplace=False, i=False):
         """Permute the axes of the data array.
 
-        .. seealso:: `flatten', `insert_dimension`, `flip`, `squeeze`,
+        .. seealso:: `flatten`, `insert_dimension`, `flip`, `squeeze`,
                      `swapaxes`
 
         :Parameters:

cf/field.py

@@ -5441,7 +5441,7 @@ def collapse(
         field construct.
 
         *Example:*
-          Calculate the temporal maximum of the weighted areal means
+          Calculate the temporal maximum of the weighted area means
           using two independent calls:
 
           >>> b = a.collapse('area: mean', weights=True).collapse('T: maximum')
@@ -5452,7 +5452,7 @@ def collapse(
         specifies each axis, and a space delimits the separate collapses).
 
         *Example:*
-          Calculate the temporal maximum of the weighted areal means in
+          Calculate the temporal maximum of the weighted area means in
           a single call, using the cf-netCDF cell methods-like syntax:
 
           >>> b =a.collapse('area: mean T: maximum', weights=True)
@@ -6068,7 +6068,7 @@ def collapse(
                                    numbers of elements.
 
                                  * The start of the first group may be
-                                   before the first first axis element,
+                                   before the first axis element,
                                    depending on the offset defined by the
                                    time duration. For example, if
                                    ``group=cf.Y(month=12)`` then the first