DOC: Correct typos in developer guide for consistency (#60932)

* DOC: Correct a typo in contributing_codebase.rst

* DOC: Correct another typo in developer.rst

Author: star1327p

doc/source/development/contributing_codebase.rst

@@ -344,7 +344,7 @@ be located.
    - tests.scalar
    - tests.tseries.offsets
 
-2. Does your test depend only on code in pd._libs?
+2. Does your test depend only on code in ``pd._libs``?
    This test likely belongs in one of:
 
    - tests.libs

doc/source/development/developer.rst

@@ -99,7 +99,7 @@ Column metadata
 * Boolean: ``'bool'``
 * Integers: ``'int8', 'int16', 'int32', 'int64', 'uint8', 'uint16', 'uint32', 'uint64'``
 * Floats: ``'float16', 'float32', 'float64'``
-* Date and Time Types: ``'datetime', 'datetimetz'``, ``'timedelta'``
+* Date and Time Types: ``'datetime', 'datetimetz', 'timedelta'``
 * String: ``'unicode', 'bytes'``
 * Categorical: ``'categorical'``
 * Other Python objects: ``'object'``