syntax: gentoo: make it clearer that the file contains two syntaxes

syntax/gentoo.nanorc

-## Here is an example for Gentoo ebuilds/eclasses.
+## Here is an example for Gentoo ebuilds/eclasses,
+## and (further down) one for Portage control files.
 
 syntax "ebuild" "\.e(build|class|blit)$"
 comment "#"
 
-## All the standard portage functions
+## All the standard portage functions:
 color brightgreen "(^|\<default_)src_(unpack|prepare|configure|compile|install|test)\>"
 color brightgreen "^pkg_(config|nofetch|info|pretend|setup|(pre|post)(inst|rm))\>"
 color brightgreen "\<default(_pkg_nofetch|_src_(unpack|prepare|configure|compile|test))?\>"
-## Highlight bash related syntax
+## Bash-related syntax:
 color green "\<(break|case|continue|do|done|elif|else|esac|exit|fi|for|function|if|in|read|return|select|shift|then|time|until|while)\>"
 color green "\<(declare|eval|exec|export|let|local)\>"
 color green "[{}():;|`$<>!=&\\]" "(\]|\[)"
 color green "-[defhnrsuwxzL]\>"
 color green "-(eq|ne|gt|lt|ge|le)\>"
-## Highlight variables ... official portage ones in red, all others in bright red
+## Variables... official portage ones in red, all others in bright red:
 color brightred "\$[-0-9@*#?$!]" "\$[[:alpha:]_][[:alnum:]_]*"
 color brightred "\$\{[#!]?([-@*#?$!]|[0-9]+|[[:alpha:]_][[:alnum:]_]*)(\[([[:digit:]]|@)+\])?(([#%/]|:?[-=?+])[^}]*\}|\[|\})"
 color red "\<(EAPI|ARCH|HOMEPAGE|DESCRIPTION|IUSE|SRC_URI|LICENSE|SLOT|KEYWORDS|[HPR]?DEPEND|PROVIDE|PROPERTIES|REQUIRED_USE|RESTRICT|USERLAND)\>"
@@ -22,7 +23,7 @@ color red "\<(AS|C(PP|XX)?|LD)FLAGS\>" "\<C(HOST|TARGET|BUILD)\>" "\<(MERGE_TYPE
 color red "\<EBUILD_PHASE(_FUNC)?\>"
 color red "\<QA_((TEXTRELS|EXECSTACK|WX_LOAD)(_[a-zA-Z_0-9]+)?|DT_HASH|PRESTRIPPED)\>"
 color red "\<(PATCHES|(HTML_)?DOCS)\>" "\<WANT_(AUTO(CONF|MAKE)|LIBTOOL)\>" "\<AT_M4DIR\>"
-## Highlight portage commands
+## Portage commands:
 color magenta "\<(use(_(with|enable|if_iuse)|x)?|in_iuse)\> [!a-zA-Z0-9_+ -]*" "inherit.*"
 color brightblue "\<e(begin|end|conf|install|make|qmake4|ant|(qa)?warn|infon?|error|log|patch(_user)?|new(group|user))\>"
 color brightblue "\<e(pause|beep|mktemp|(cvs|svn)_clean|punt_cxx)\>" "\<e(aclocal|auto(reconf|header|conf|make)|libtoolize)\>"
@@ -35,20 +36,21 @@ color brightblue "\<prepall(docs|info|man|strip)?\>" "\<prep(info|lib|lib\.(so|a
 color brightblue "\<(doc|ins|exe)?into\>" "\<(f|games)(owners|perms)\>" "\<(exe|ins|dir)opts\>"
 color brightblue "\<tc-get(BUILD_)?(AR|AS|CC|CPP|CXX|LD|NM|OBJCOPY|PKG_CONFIG|RANLIB)\>"
 color brightblue "\<tc-(arch(-kernel)?|export|has-(tls|openmp))\>"
-## Highlight common commands used in ebuilds
+## Common commands used in ebuilds:
 color blue "\<(awk|cat|cd|chmod|chown|cp|echo|env|find|e?grep|ln|make|mkdir|mv|popd|printf|pushd|rm|rmdir|sed|set|tar|touch|unset|xargs)\>"
-## Highlight comments (doesnt work that well)
+## Comments (doesn't work that well):
 color yellow "(^|[[:space:]])#.*$"
-## Highlight strings (doesnt work that well)
+## Strings (doesn't work that well):
 color brightyellow ""(\\.|[^\"])*"" "'(\\.|[^'])*'"
 ## Trailing space is bad!
 color ,green "[[:space:]]+$"
 ## Mixed whitespace is also bad.
 color ,green " 	"
 
-## Here is an example for Portage control files.
-##
+
 syntax "/etc/portage" "\.(accept_keywords|env|keywords|mask|unmask|use)(/.+)?$"
+comment "#"
+
 ## Base text:
 color green "^.+$"
 ## Likely version and slot numbers: