[bash] Fix some spell errors in comments

bash.html.markdown

@@ -94,12 +94,12 @@ python2 hello.py 2> "error.err"
 # The output error will overwrite the file if it exists, if you want to
 # concatenate them, use ">>" instead.
 
-# Commands can be substitued within other commands using $( ):
+# Commands can be substituted within other commands using $( ):
 # The following command displays the number of files and directories in the
 # current directory.
 echo "There are $(ls | wc -l) items here."
 
-# Bash uses a case statement that works similarily to switch in Java and C++:
+# Bash uses a case statement that works similarly to switch in Java and C++:
 case "$VARIABLE" in 
     #List patterns for the conditions you want to meet
     0) echo "There is a zero.";;