docs: Fix a few typos

There are small typos in:
- libc/stdio/appendr.c
- third_party/infozip/zip/api.c
- third_party/quickjs/qjscalc.js
- third_party/stb/stb_image.c

Fixes:
- Should read `occurrence` rather than `occurance`.
- Should read `guaranteed` rather than `guarranteed`.
- Should read `guarantee` rather than `guarante`.
- Should read `function` rather than `fonction`.

libc/stdio/appendr.c

@@ -39,7 +39,7 @@
  * If `i` is greater than the current length then the extra bytes are
  * filled with NUL characters.
  *
- * The resulting buffer is guarranteed to be NUL-terminated, i.e.
+ * The resulting buffer is guaranteed to be NUL-terminated, i.e.
  * `!b[appendz(b).i]` will be the case.
  *
  * @return `i` or -1 if `ENOMEM`

third_party/infozip/zip/api.c

@@ -99,7 +99,7 @@ if ((szRootDir != NULL) && (szRootDir[0] != '\0'))
 else
     root_flag = FALSE;
 
-str2 = strchr(str1, '\"'); /* get first occurance of double quote */
+str2 = strchr(str1, '\"'); /* get first occurrence of double quote */
 
 while ((str3 = strchr(str1, '\t')) != NULL)
     {
@@ -151,7 +151,7 @@ while ((str2 = strchr(str1, '\"')) != NULL)
     lstrcat(str1, str3);
     }    /* end while */
 
-/* points to first occurance of a space */
+/* points to first occurrence of a space */
 str2 = strchr(str1, ' ');
 
 /*  Go through the string character by character, looking for instances

third_party/quickjs/qjscalc.js

@@ -1615,7 +1615,7 @@ var Integer, Float, Fraction, Complex, Mod, Polynomial, PolyMod, RationalFunctio
                 return v1;
             v2_emin = 0;
         } else if (v2 instanceof RationalFunction) {
-            /* compute the emin of the rational fonction */
+            /* compute the emin of the rational function */
             i = get_emin(v2.num) - get_emin(v2.den);
             if (d <= i)
                 return v1;

third_party/stb/stb_image.c

@@ -2908,7 +2908,7 @@ static int stbi__create_png_image_raw(stbi__png *a, unsigned char *raw,
       unsigned char *cur = a->out + stride * j;
       unsigned char *in = a->out + stride * j + x * out_n - img_width_bytes;
       // unpack 1/2/4-bit into a 8-bit buffer. allows us to keep the common
-      // 8-bit path optimal at minimal cost for 1/2/4-bit png guarante byte
+      // 8-bit path optimal at minimal cost for 1/2/4-bit png guarantee byte
       // alignment, if width is not multiple of 8/4/2 we'll decode dummy
       // trailing data that will be skipped in the later loop
       unsigned char scale = (color == 0)