Fix tutorial typos. (matplotlib#12457)

Quotes were missing in `rcParams["axes.titlepad"]`.
Capitalize a few instances of "Matplotlib".

Author: anntzer

tutorials/text/text_intro.py

@@ -14,7 +14,7 @@
 or PDF, what you see on the screen is what you get in the hardcopy.
 `FreeType <https://www.freetype.org/>`_ support
 produces very nice, antialiased fonts, that look good even at small
-raster sizes.  matplotlib includes its own
+raster sizes.  Matplotlib includes its own
 :mod:`matplotlib.font_manager` (thanks to Paul Barrett), which
 implements a cross platform, `W3C <http://www.w3.org/>`
 compliant font finding algorithm.
@@ -23,7 +23,7 @@
 weight, text location and color, etc.) with sensible defaults set in
 the :doc:`rc file </tutorials/introductory/customizing>`.
 And significantly, for those interested in mathematical
-or scientific figures, matplotlib implements a large number of TeX
+or scientific figures, Matplotlib implements a large number of TeX
 math symbols and commands, supporting :doc:`mathematical expressions
 </tutorials/text/mathtext>` anywhere in your figure.
 
@@ -211,8 +211,8 @@
 plt.show()
 
 ##############################################################################
-# Vertical spacing for titles is controlled via ``rcParams[axes.titlepad]``,
-# which defaults to 5 points.  Setting to a different value moves the title.
+# Vertical spacing for titles is controlled via :rc:`axes.titlepad`, which
+# defaults to 5 points.  Setting to a different value moves the title.
 
 fig, ax = plt.subplots(figsize=(5, 3))
 fig.subplots_adjust(top=0.8)