7903755: multi header support and special syntax for header file

doc/GUIDE.md

@@ -60,7 +60,7 @@ Note that specifying the wrong header file to jextract may result in errors duri
 Please consult the documentation of the library in question about which header file
 should be included. This is also the header file that should be passed to jextract.
 
-If a library has multiple main header files, they can be passed to jextract in the command line.
+If a library has multiple main header files, they can be passed to jextract on the command line.
 Also, there is special syntax to pass header files relative to C compiler include paths.
 The section on [command line option reference](#command-line-option-reference) discusses this.
 
@@ -978,7 +978,7 @@ A complete list of all the supported command line options is given below:
 | Option                                                       | Meaning                                                      |
 | :----------------------------------------------------------- | ------------------------------------------------------------ |
 | `-D --define-macro <macro>=<value>`                          | define `<macro>` to `<value>` (or 1 if `<value>` omitted)          |
-| `--header-class-name <name>`                                 | name of the generated header class. If this option is not specified, then header class name is derived from the header file name. For example, class "foo_h" for header "foo.h". |
+| `--header-class-name <name>`                                 | name of the generated header class. If this option is not specified, then header class name is derived from the header file name. For example, class "foo_h" for header "foo.h". If multiple headers are specified, then this option is mandatory. |
 | `-t, --target-package <package>`                             | target package name for the generated classes. If this option is not specified, then unnamed package is used.  |
 | `-I, --include-dir <dir>`                                    | append directory to the include search paths. Include search paths are searched in order. For example, if `-I foo -I bar` is specified, header files will be searched in "foo" first, then (if nothing is found) in "bar".|
 | `-l, --library <name \| path>`                               | specify a shared library that should be loaded by the generated header class. If <libspec> starts with `:`, then what follows is interpreted as a library path. Otherwise, `<libspec>` denotes a library name. Examples: <br>`-l GL`<br>`-l :libGL.so.1`<br>`-l :/usr/lib/libGL.so.1`|
@@ -998,7 +998,7 @@ the `--header-class-name` option is mandatory. Header files can be specified in
       in the C compiler include path. This simplifies the extraction of header files
       from standard include paths and include paths specified by `-I` options.
 
-      Note that '>' and '<' are special characters in OS Shells and therefore those
+      Note that `>` and `<` are special characters in OS Shells and therefore those
       need to be escaped appropriately. On Unix platforms, simple quoting like `"<stdio.h>"`
       is enough.