Make line length, wrapping and spacing consistent

doc_src/echo.txt

@@ -12,9 +12,13 @@ echo [OPTIONS] [STRING]
 The following options are available:
 
 - `-n`, Do not output a newline
+
 - `-s`, Do not separate arguments with spaces
+
 - `-E`, Disable interpretation of backslash escapes (default)
+
 - `-e`, Enable interpretation of backslash escapes
+
 - `-h`, `--help` Display this help
 
 \subsection echo-escapes Escape Sequences
@@ -22,20 +26,35 @@ The following options are available:
 If `-e` is used, the following sequences are recognized:
 
 - `\` backslash
+
 - `\a` alert (BEL)
+
 - `\b` backspace
+
 - `\c` produce no further output
+
 - `\e` escape
+
 - `\f` form feed
+
 - `\n` new line
+
 - `\r` carriage return
+
 - `\t` horizontal tab
+
 - `\v` vertical tab
+
 - `\0NNN` byte with octal value NNN (1 to 3 digits)
+
 - `\xHH` byte with hexadecimal value HH (1 to 2 digits)
 
 \subsection echo-example Example
 
-`echo 'Hello World'` Print hello world to stdout
+\fish
+echo 'Hello World'
+# Print hello world to stdout
 
-`echo -e 'Top\nBottom'` Print Top and Bottom on separate lines, using an escape sequence
+echo -e 'Top\nBottom'
+# Print Top and Bottom on separate lines, using an escape sequence
+\endfish