Fix two sphinx warnings for docs build (#1285)

Specifically in pygmt/src/wiggle.py and pygmt/clib/session.py

Author: Meghan Jones

pygmt/clib/session.py

@@ -734,7 +734,7 @@ def _check_dtype_and_dim(self, array, ndim):
         return self[DTYPES[array.dtype.type]]
 
     def put_vector(self, dataset, column, vector):
-        """
+        r"""
         Attach a numpy 1D array as a column on a GMT dataset.
 
         Use this function to attach numpy array data to a GMT dataset and pass
@@ -744,7 +744,7 @@ def put_vector(self, dataset, column, vector):
         first. Use ``family='GMT_IS_DATASET|GMT_VIA_VECTOR'``.
 
         Not at all numpy dtypes are supported, only: float64, float32, int64,
-        int32, uint64, uint32, datetime64 and str_.
+        int32, uint64, uint32, datetime64 and str\_.
 
         .. warning::
             The numpy array must be C contiguous in memory. If it comes from a

pygmt/src/wiggle.py

@@ -56,7 +56,7 @@ def wiggle(self, x=None, y=None, z=None, data=None, **kwargs):
     {B}
     position : str
         [**g**\|\ **j**\|\ **J**\|\ **n**\|\ **x**]\ *refpoint*\
-        **+w**\ *length*\ [**+j**\ *justify*]\ [**+al**\ |\ **r**]\
+        **+w**\ *length*\ [**+j**\ *justify*]\ [**+al**\|\ **r**]\
         [**+o**\ *dx*\ [/*dy*]][**+l**\ [*label*]].
         Defines the reference point on the map for the vertical scale bar.
     color : str