Fix typos in docstrings of "pygmt.Figure.histogram" (#2457)

pygmt/src/histogram.py

@@ -61,16 +61,16 @@ def histogram(self, data, **kwargs):
  {panel}
  annotate : bool or str
  [**+b**][**+f**\ *font*][**+o**\ *off*][**+r**].
- Annotate each bar with the count it represents.  Append any of the
+ Annotate each bar with the count it represents. Append any of the
  following modifiers: Use **+b** to place the labels beneath the bars
  instead of above; use **+f** to change to another font than the default
  annotation font; use **+o** to change the offset between bar and
- label [6p]; use **+r** to rotate the labels from horizontal to
- vertical.
+ label [Default is ``"6p"``]; use **+r** to rotate the labels from
+ horizontal to vertical.
  barwidth : int or float or str
  *width*\ [**+o**\ *offset*].
  Use an alternative histogram bar width than the default set via
- ``series``, and optionally shift all bars by an *offset*.  Here
+ ``series``, and optionally shift all bars by an *offset*. Here
  *width* is either an alternative width in data units, or the user may
  append a valid plot dimension unit (**c**\|\ **i**\|\ **p**) for a
  fixed dimension instead. Optionally, all bins may be shifted along the
@@ -81,7 +81,7 @@ def histogram(self, data, **kwargs):
  distribution : bool or int or float or str
  [*mode*][**+p**\ *pen*].
  Draw the equivalent normal distribution; append desired
- *pen* [Default is 0.25p,black].
+ *pen* [Default is ``"0.25p,black,solid"``].
  The *mode* selects which central location and scale to use:
 
  * 0 = mean and standard deviation [Default];
@@ -94,7 +94,7 @@ def histogram(self, data, **kwargs):
  extreme : str
  **l**\|\ **h**\|\ **b**.
  The modifiers specify the handling of extreme values that fall outside
- the range set by ``series``.  By default these values are ignored.
+ the range set by ``series``. By default, these values are ignored.
  Append **b** to let these values be included in the first or last
  bins. To only include extreme values below first bin into the first
  bin, use **l**, and to only include extreme values above the last bin